Moar doc

gclient_scm.py

Index: gclient_scm.py
diff --git a/gclient_scm.py b/gclient_scm.py
index 3a9e90ed6d55c5558464ddd0720f5eac12effab5..31296d02d13df72e058b2afff6dc9e6c261ee2d3 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -1031,6 +1031,13 @@ class GitWrapper(SCMWrapper):
                                       kwargs.get('filter_fn'))
       kwargs.setdefault('print_stdout', False)
       # Don't prompt for passwords; just fail quickly and noisily.
+      # By default, git will use an interactive terminal prompt when a username/
+      # password is needed.  That shouldn't happen in the chromium workflow,
+      # and if it does, then gclient may hide the prompt in the midst of a flood
+      # of terminal spew.  The only indication that something has gone wrong
+      # will be when gclient hangs unresponsively.  Instead, we disable the
+      # password prompt and simply allow git to fail noisily.  The error
+      # message produced by git will be copied to gclient's output.

[Dirk Pranke, 2013/07/10 00:54:26]

nit: this doesn't mention why we need to set SSH_ASKPASS also. Is that needed? 

You could also delete "That shouldn't happen in the chromium workflow, and if it
does, then" without losing much.

       env = kwargs.get('env') or kwargs.setdefault('env', os.environ.copy())

[M-A Ruel, 2013/07/10 01:02:50]

In general I'd recommend:
env = kwargs.setdefault('env', os.environ.copy())

In practice the code you wrote saves a dict copy but it's python, so we prefer
readability over performance in general.

       env.setdefault('GIT_ASKPASS', 'true')
       env.setdefault('SSH_ASKPASS', 'true')