Allow a commit message to be specified to merge-to-branch.sh

Allow a commit message to be specified to merge-to-branch.sh

R=jkummerow@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=11181

[Jakob Kummerow, 2012-03-28 07:44:04]

lgtm

[danno, 2012-03-28 09:48:22]

please take another quick look

[Jakob Kummerow, 2012-03-28 09:54:05]

Still LGTM.

We'll have to extend it when someone wants to store "__EMPTY__" in a variable,
though :-)

[Sven Panne, 2012-03-28 11:40:39]

https://chromiumcodereview.appspot.com/9844015/diff/3002/tools/common-include...
File tools/common-includes.sh (right):

https://chromiumcodereview.appspot.com/9844015/diff/3002/tools/common-include...
tools/common-includes.sh:90: local VALUE="$(cat $FILE)"
I'm just curious: Why is this detour via __EMPTY__ necessary? The echo/cat combo
seems to do the right thing even for empty strings, but probably I'm missing
something...

[Jakob Kummerow, 2012-03-28 11:43:49]

On 2012/03/28 11:40:39, Sven Panne wrote:
> I'm just curious: Why is this detour via __EMPTY__ necessary? The echo/cat
combo
> seems to do the right thing even for empty strings, but probably I'm missing
> something...

Persisting and restoring an empty variable would indeed work just fine; but the
check whether restoring was successful would fail. We could have removed the
check, but it has been useful to find errors in the past, so we decided to use a
sentinel value for "successfully restored but still empty" instead.