Moar doc

gclient_scm.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Gclient-specific SCM-specific operations."""
 
 import collections
 import logging
 import os
 import posixpath
@@ skipping 1013 matching lines @@
 
   def _Run(self, args, _options, git_filter=False, **kwargs):
     kwargs.setdefault('cwd', self.checkout_path)
     kwargs.setdefault('nag_timer', self.nag_timer)
     kwargs.setdefault('nag_max', self.nag_max)
     if git_filter:
       kwargs['filter_fn'] = GitFilter(kwargs['nag_timer'] / 2,
                                       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')
     else:
       kwargs.setdefault('print_stdout', True)
     stdout = kwargs.get('stdout', sys.stdout)
     stdout.write('\n________ running \'git %s\' in \'%s\'\n' % (
                  ' '.join(args), kwargs['cwd']))
     gclient_utils.CheckCallAndFilter(['git'] + args, **kwargs)
 
 
@@ skipping 380 matching lines @@
       new_command.append('--force')
       if command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
         new_command.extend(('--accept', 'theirs-conflict'))
     elif options.manually_grab_svn_rev:
       new_command.append('--force')
       if command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
         new_command.extend(('--accept', 'postpone'))
     elif command[0] != 'checkout' and scm.SVN.AssertVersion('1.6')[0]:
       new_command.extend(('--accept', 'postpone'))
     return new_command