Added git hyper-blame, a tool that skips unwanted commits in git blame.

git_common.py

Index: git_common.py
diff --git a/git_common.py b/git_common.py
index 506365257ecd63556258f4656350cd3240142f2d..5dd42b01d35caa2e0c5b80627e234f875e0c9e0b 100644
--- a/git_common.py
+++ b/git_common.py
@@ -281,6 +281,16 @@ def once(function):
 ## Git functions
 
 
+def blame(filename, revision=None, porcelain=False, *args):
+  command = ['blame']
+  if porcelain:  # pragma: no cover

[iannucci, 2016/01/29 19:29:25]

why not covered?

[Matt Giuca, 2016/02/01 03:51:06]

Testing porcelain was a lot of work, and covered implicitly by hyper-blame
tests.

Well, I've added porcelain tests.

+    command.append('-p')
+  if revision is not None:
+    command.append(revision)

[iannucci, 2016/01/29 19:29:25]

may want to consider -w and -M options

[Matt Giuca, 2016/02/01 03:51:06]

I think we could consider that in a future version. I don't think we want that
to be the default for hyper-blame (which has the specific goal of ignoring
certain commits, not necessarily bypassing other arbitrary changes).

+  command.extend(['--', filename])
+  return run(*command)
+
+
 def branch_config(branch, option, default=None):
   return config('branch.%s.%s' % (branch, option), default=default)
 
@@ -546,10 +556,39 @@ def remove_merge_base(branch):
   del_branch_config(branch, 'base-upstream')
 
 
+def repo_root():  # pragma: no cover

[iannucci, 2016/01/29 19:29:25]

?

[Matt Giuca, 2016/02/01 03:51:06]

I didn't think it would be easy to test this since it's in a random directory.
But it was kind of easy. Done.

+  """Returns the absolute path to the repository root."""
+  return run('rev-parse', '--show-toplevel')
+
+
 def root():
   return config('depot-tools.upstream', 'origin/master')
 
 
+@contextlib.contextmanager
+def less():  # pragma: no cover
+  """Runs 'less' as context manager yielding its stdin as a PIPE.
+
+  Automatically checks if sys.stdout is a non-TTY stream. If so, it avoids
+  running less and just yields sys.stdout.
+  """

[iannucci, 2016/01/29 19:29:25]

does this work on windows?

Generally stuff in depot_tools at least tries to work in windows too... I would
at least try to make linux features gracefully degrade. If running it with `git
bash` is sufficient, I would detect a non-bash environment, print an error to
that effect and exit.

[Matt Giuca, 2016/02/01 03:51:06]

Tested on Windows; works perfectly, except for an IOError if you quit less
before getting to the end. Added a catch for that.

Tested on both MinGW and cmd, for both regular terminal output and piping to a
file. I'm a bit surprised that less worked from cmd, given that typing "less"
doesn't work on the command line. But it seems to be fine.

Tests almost completely fail, but that's also true of git_common_test so I think
there is just something bad about the testing environment on Windows and
probably not worth looking into.

+  if not sys.stdout.isatty():
+    yield sys.stdout
+    return
+
+  # Run with the same options that git uses (see setup_pager in git repo).
+  # -F: Automatically quit if the output is less than one screen.
+  # -R: Don't escape ANSI color codes.
+  # -X: Don't clear the screen before starting.
+  cmd = ('less', '-FRX')
+  try:
+    proc = subprocess2.Popen(cmd, stdin=subprocess2.PIPE)
+    yield proc.stdin
+  finally:
+    proc.stdin.close()
+    proc.wait()
+
+
 def run(*cmd, **kwargs):
   """The same as run_with_stderr, except it only returns stdout."""
   return run_with_stderr(*cmd, **kwargs)[0]