Add git thaw/freeze to depot_tools.

git_common.py

Index: git_common.py
diff --git a/git_common.py b/git_common.py
index fa6d3fc75556b1e4a9a61724315eee4ab4fd9f7c..71db99a8489fea82219c43204384c80adc426927 100644
--- a/git_common.py
+++ b/git_common.py
@@ -153,7 +153,7 @@ def ScopedPool(*args, **kwargs):
 
 class ProgressPrinter(object):
   """Threaded single-stat status message printer."""
-  def __init__(self, fmt, enabled=None, stream=sys.stderr, period=0.5):
+  def __init__(self, fmt, enabled=None, fout=sys.stderr, period=0.5):
     """Create a ProgressPrinter.
 
     Use it as a context manager which produces a simple 'increment' method:
@@ -169,7 +169,7 @@ class ProgressPrinter(object):
         should go.
       enabled (bool) - If this is None, will default to True if
         logging.getLogger() is set to INFO or more verbose.
-      stream (file-like) - The stream to print status messages to.
+      fout (file-like) - The stream to print status messages to.
       period (float) - The time in seconds for the printer thread to wait
         between printing.
     """
@@ -182,7 +182,7 @@ class ProgressPrinter(object):
     self._count = 0
     self._dead = False
     self._dead_cond = threading.Condition()
-    self._stream = stream
+    self._stream = fout
     self._thread = threading.Thread(target=self._run)
     self._period = period
 
@@ -256,17 +256,26 @@ def run(*cmd, **kwargs):
 
   kwargs
     autostrip (bool) - Strip the output. Defaults to True.
-  Output string is always strip()'d.
   """
   autostrip = kwargs.pop('autostrip', True)
-  cmd = (GIT_EXE,) + cmd
-  logging.debug('Running %s', ' '.join(repr(tok) for tok in cmd))
-  ret = subprocess2.check_output(cmd, stderr=subprocess2.PIPE, **kwargs)
+  ret = stream(*cmd, **kwargs).read()
   if autostrip:
     ret = (ret or '').strip()
   return ret
 
 
+def stream(*cmd, **kwargs):
+  """Runs a git command. Returns stdout as a file.
+
+  If logging is DEBUG, we'll print the command before we run it.
+  """
+  cmd = (GIT_EXE,) + cmd
+  logging.debug('Running %s', ' '.join(repr(tok) for tok in cmd))
+  proc = subprocess2.Popen(cmd, stderr=subprocess2.VOID,
+                           stdout=subprocess2.PIPE, **kwargs)
+  return proc.stdout
+
+
 def hash_one(reflike):
   return run('rev-parse', reflike)