Allow gclient clone in non-empty directories

gclient.py

Index: gclient.py
diff --git a/gclient.py b/gclient.py
index ed08e47f423cb96bbd6ba9c9ca2902cbc394cc62..9c4077153edbc41fe0155d5408dd3c27c5c84b53 100755
--- a/gclient.py
+++ b/gclient.py
@@ -288,7 +288,8 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
   """Object that represents a dependency checkout."""
 
   def __init__(self, parent, name, url, safesync_url, managed, custom_deps,
-               custom_vars, custom_hooks, deps_file, should_process):
+               custom_vars, custom_hooks, deps_file, should_process,
+               tmpdir_stage):
     gclient_utils.WorkItem.__init__(self, name)
     DependencySettings.__init__(
         self, parent, url, safesync_url, managed, custom_deps, custom_vars,
@@ -313,6 +314,7 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     # This is the scm used to checkout self.url. It may be used by dependencies
     # to get the datetime of the revision we checked out.
     self._used_scm = None
+    self.tmpdir_stage = tmpdir_stage
 
     if not self.name and self.parent:
       raise gclient_utils.Error('Dependency without name')
@@ -500,6 +502,8 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
       self.local_target_os = local_scope['target_os']
     # load os specific dependencies if defined.  these dependencies may
     # override or extend the values defined by the 'deps' member.
+
+    tmpdir_staged_deps = local_scope.get('tmpdir_stage', [])
     target_os_deps = {}
     if 'deps_os' in local_scope:
       for deps_os_key in self.target_os:
@@ -541,7 +545,7 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
       should_process = self.recursion_limit and self.should_process
       deps_to_add.append(Dependency(
           self, name, url, None, None, None, None, None,
-          self.deps_file, should_process))
+          self.deps_file, should_process, name in tmpdir_staged_deps))
     deps_to_add.sort(key=lambda x: x.name)
 
     # override named sets of hooks by the custom hooks
@@ -632,6 +636,7 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
         # Create a shallow copy to mutate revision.
         options = copy.copy(options)
         options.revision = revision_overrides.get(self.name)
+        options.stage_clone = self.tmpdir_stage
         self.maybeGetParentRevision(
             command, options, parsed_url, self.parent.name, revision_overrides)
         self._used_scm = gclient_scm.CreateSCM(