Add rpc: to default protocol whitelist

Change-Id: I57e1c3d93c0ce56da9c487df65eb3d258e0260e8
diff --git a/git_command.py b/git_command.py
index 63b7b6f..9f7d293 100644
--- a/git_command.py
+++ b/git_command.py
@@ -170,7 +170,7 @@
       _setenv(env, 'GIT_CONFIG_PARAMETERS', s)
     if 'GIT_ALLOW_PROTOCOL' not in env:
       _setenv(env, 'GIT_ALLOW_PROTOCOL',
-              'file:git:http:https:ssh:persistent-http:persistent-https:sso')
+              'file:git:http:https:ssh:persistent-http:persistent-https:sso:rpc')
 
     if project:
       if not cwd: