Sometimes DEPS will not pin a revision for a dependency, but just let it float

deps2git/deps2submodules.py

 #!/usr/bin/python
 # 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.
 
 """Read .DEPS.git and use the information to update git submodules"""
 
 import os
 import subprocess
 import sys
 
 from deps_utils import GetDepsContent
 
 
 def CollateDeps(deps_content):
   """
   Take the output of deps_utils.GetDepsContent and return a hash of:
 
   { submod_name : [ submod_os, submod_url, submod_sha1 ], ... }
   """
   fixdep = lambda x: x[4:] if x.startswith('src/') else x
-  spliturl = lambda x: x.split('@', 1)
+  spliturl = lambda x: list(x.partition('@')[0::2])
   submods = {}
   for (dep, url) in deps_content[0].iteritems():
     submods[fixdep(dep)] = ['all'] + spliturl(url)
   for (deps_os, val) in deps_content[1].iteritems():
     for (dep, url) in val.iteritems():
       submods[fixdep(dep)] = [deps_os] + spliturl(url)
   return submods
 
 
 def WriteGitmodules(submods):
   """
   Take the output of CollateDeps, use it to write a .gitmodules file and
   add submodules to the git index.
   """
   fh = open('.gitmodules', 'w')
   for submod in sorted(submods.keys()):
     [submod_os, submod_url, submod_sha1] = submods[submod]
     print >>fh, '[submodule "%s"]' % submod
     print >>fh, '\tpath = %s' % submod
     print >>fh, '\turl = %s' % submod_url
     print >>fh, '\tos = %s' % submod_os
+    if not submod_sha1:
+      # We don't know what sha1 to register, so we have to infer it from the
+      # submodule's origin/master.
+      if not os.path.exists(os.path.join(submod, '.git')):
+        # Not cloned yet
+        subprocess.check_call(['git', 'clone', '-n', submod_url, submod])
+      else:
+        # Already cloned; let's fetch
+        subprocess.check_call(['git', 'fetch', 'origin'], cwd=submod)
+      sub = subprocess.Popen(['git', 'rev-list', 'origin/HEAD^!'],
+                             cwd=submod, stdout=subprocess.PIPE)
+      submod_sha1 = sub.communicate()[0].rstrip()
     subprocess.check_call(['git', 'update-index', '--add',
                            '--cacheinfo', '160000', submod_sha1, submod])
   fh.close()
   subprocess.check_call(['git', 'add', '.gitmodules'])
 
 
 def RemoveObsoleteSubmodules():
   """
   Delete from the git repository any submodules which aren't in .gitmodules.
   """
@@ skipping 17 matching lines @@
 
 def main():
   deps_file = sys.argv[1] if len(sys.argv) > 1 else '.DEPS.git'
   WriteGitmodules(CollateDeps(GetDepsContent(deps_file)))
   RemoveObsoleteSubmodules()
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())