init: add -o, --origin to name manifest remote

The -o option permits the user to control the name of the manifest's
remote, which normally is hardcoded to be 'origin', but can differ
because we derive it at runtime from the configuration file.

Signed-off-by: Shawn O. Pearce <sop@google.com>

project.py

@@ -1442,10 +1442,12 @@ class MetaProject(Project):
     if self.Exists:
       cb = self.CurrentBranch
       if cb:
-        base = self.GetBranch(cb).merge
-        if base:
-          self.revisionExpr = base
+        cb = self.GetBranch(cb)
+        if cb.merge:
+          self.revisionExpr = cb.merge
           self.revisionId = None
+        if cb.remote and cb.remote.name:
+          self.remote.name = cb.remote.name
 
   @property
   def LastFetch(self):