Handle updating depot_tools repos that are git cloned.

Handle updating depot_tools repos that are git cloned.

Until recently, no proper Git clone of depot_tools existed.
All Git clones were set up locally via git svn clone.  The
way repos of that type are updated is via 'git svn rebase'.

Now, a supported Git clone of depot_tools exists.  The
update process for repos of this type is via 'git fetch'
and 'git rebase'.

Modify the update_depot_tools* scripts so they can update
depot_tools for git cloned or git svn cloned methods.  This
also means that git svn is no longer required, so move that
test after we check for git cloned repos.

R=maruel@chromium.org

TEST=Linux + git clone: on Linux, git clone
https://git.chromium.org/chromium/tools/depot_tools.git.  Apply
and commit this patch locally.  Note commit hash of HEAD.  Run
'git reset --hard "HEAD^^^"'.  Run
'git cherry-pick HASH_OF_UPDATE_CHANGE'.  Run './update_depot_tools'.
Verify depot_tools is updated to latest available revision + this
change.

TEST=Linux + git svn clone: on Linux, git svn clone
svn://svn.chromium.org/chrome/trunk/tools/depot_tools.
Apply and commit this patch locally.  Note commit hash
of HEAD.  Run 'git reset --hard "HEAD^^^"'.  Run 'git cherry-pick
HASH_OF_UPDATE_CHANGE'.  Run './update_depot_tools'.  Verify
depot_tools is updated to latest available revision + this change.

TEST=Windows command prompt + git clone: on Windows command prompt,
run Linux+git clone test, except use update_depot_tools.bat.  Verify
depot_tools is updated to latest available revision + this change.

TEST=Windows command prompt + git svn clone: on Windows command
prompt, run Linux+git svn clone test, except use
update_depot_tools.bat.  Verify depot_tools is updated to latest
available revision + this change.

TEST=Windows cygwin + git clone: on Windows command prompt,
run Linux+git clone test.  Verify depot_tools is updated to latest
available revision + this change.

TEST=Windows cygwin + git svn clone: on Windows command
prompt, run Linux+git svn clone test.  Verify depot_tools is updated
to latest available revision + this change.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=134732

[cmp, 2012-04-29 00:12:22]

So far I verified the Linux tests and the first Windows command prompt test. 
The second Windows command prompt test takes forever to git svn clone, that will
run for a while before I can verify it works.

[cmp, 2012-04-29 00:19:41]

expanded the Windows tests described in changelog (a local changelog edit I
didn't make in my repo in time)

[cmp, 2012-04-29 00:20:11]

fixed the cygwin tests to be exactly like the linux tests.  that is, they should
now use update_depot_tools.bat, they should use update_depot_tools.

[cmp, 2012-04-29 00:23:58]

the following tests are verified:
- Linux + git clone
- Linux + git svn clone
- Windows command prompt + git clone
- Windows cygwin + git clone

the following tests are not yet verified:
- Windows command prompt + git svn clone
- Windows cygwin + git svn clone

[M-A Ruel, 2012-04-29 00:49:08]

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools.bat
File update_depot_tools.bat (right):

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools.bat...
update_depot_tools.bat:34: call git config remote.origin.fetch > NUL
I prefer to do the reverse order of the check. First check for git svn, then
check for a remote.

The reason is that I git svn clone, then git clone this svn clone and also setup
git svn on it. So I end up with one (or 2) git remotes and one git-svn remote.

As such, I want the git svn remote to have higher priority.

[M-A Ruel, 2012-04-29 00:55:58]

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools
File update_depot_tools (right):

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools#new...
update_depot_tools:77: if is_git_clone_repo
the rest of the file uses the style:
"if is_git_clone_repo; then"

[cmp, 2012-04-29 00:57:03]

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools.bat
File update_depot_tools.bat (right):

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools.bat...
update_depot_tools.bat:34: call git config remote.origin.fetch > NUL
I asked M-A over IM if he would explain why he wouldn't just switch to use the
supported Git repo for depot_tools after this change lands, to which he replied
"ok."  So the current patchset is still the preferred way to go.

Before this would land, I'll send a PSA to users on chromium-dev@ letting them
know that they should switch any Git-based copy of depot_tools to use the new
supported repo.

[cmp, 2012-04-30 03:16:16]

Patch updated, PTAL.

The Windows+command prompt+git svn clone case was failing for an unknown reason.
 It turns out that errorlevel needs to be unset after it was set earlier by the
call to win_tools.bat.  If I unset errorlevel, then the call to git config can
set it.

Coincidentally, at one point while debugging this over the weekend I had
commented out setlocal, which caused errorlevel to be set in my command prompt. 
This was the cause of my command prompt tests of obviously bad commands leading
to 'echo %errorlevel%' printing 0.  After I unset errorlevel, then the commands
could properly set it and show that they exited in failure.

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools
File update_depot_tools (right):

https://chromiumcodereview.appspot.com/10263004/diff/1/update_depot_tools#new...
update_depot_tools:77: if is_git_clone_repo
Done.

When writing this, I saw:

if ...; then

if ...;
then

and

if ...
then

[cmp, 2012-04-30 03:25:45]

On 2012/04/29 00:23:58, cmp wrote:
> the following tests are verified:
> - Linux + git clone
> - Linux + git svn clone
> - Windows command prompt + git clone
> - Windows cygwin + git clone
> 
> the following tests are not yet verified:
> - Windows command prompt + git svn clone
> - Windows cygwin + git svn clone

All the tests have now been run, though I took a shortcut and only tested the
absolute latest patch on the "Windows cygwin + git svn clone" test.  The
"Windows command prompt + git svn clone" was tested using patch set 2.  The rest
of the tests were run using patch set 1.  Please LMK if you think I should
repeat the tests using the latest patch set.

[M-A Ruel, 2012-04-30 14:17:34]

lgtm

https://chromiumcodereview.appspot.com/10263004/diff/2002/update_depot_tools
File update_depot_tools (right):

https://chromiumcodereview.appspot.com/10263004/diff/2002/update_depot_tools#...
update_depot_tools:66: function is_git_clone_repo {
Why isn't this sufficient? My bash-fu is lacking.

function is_git_clone_repo {
  "$GIT" config remote.origin.fetch > /dev/null
}

or at worst:

function is_git_clone_repo {
  "$GIT" config remote.origin.fetch > /dev/null
  return $?
}

[cmp, 2012-04-30 18:12:37]

ptal

https://chromiumcodereview.appspot.com/10263004/diff/2002/update_depot_tools
File update_depot_tools (right):

https://chromiumcodereview.appspot.com/10263004/diff/2002/update_depot_tools#...
update_depot_tools:66: function is_git_clone_repo {
That's a great suggestion.  I didn't realize that without return functions
returned the exit status of the last command they ran.  I verified it worked and
made it.

[M-A Ruel, 2012-04-30 18:24:21]

lgtm

[cmp, 2012-05-01 17:21:36]

ptal, i added redirecting output to null to reduce noise

[M-A Ruel, 2012-05-01 17:28:17]

lgtm

[commit-bot: I haz the power, 2012-05-01 17:54:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/cmp@chromium.org/10263004/13001

[commit-bot: I haz the power, 2012-05-01 17:55:00]

Can't apply patch for file depot_tools/update_depot_tools.bat.
While running patch -p1 --forward --force;
patching file depot_tools/update_depot_tools.bat
Hunk #1 FAILED at 13.
Hunk #2 FAILED at 31.
2 out of 2 hunks FAILED -- saving rejects to file
depot_tools/update_depot_tools.bat.rej

[M-A Ruel, 2012-05-01 17:58:52]

On 2012/05/01 17:55:00, I haz the power (commit-bot) wrote:
> Can't apply patch for file depot_tools/update_depot_tools.bat.

Just commit manually.