Add <add-remote to-project="..."> to inject additional remotes

This way users can add forks they know about to an existing project
that was already declared in the primary manifest.  This is mostly
useful with the Linux kernel project, where multiple forks is quite
common for the main upstream tree (e.g. Linus' tree), a platform
architecture tree (e.g. ARM) and a device specific tree (e.g. the
msm7k tree used by Android).

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

manifest.py

@@ -165,6 +165,16 @@ class Manifest(object):
                 (project.name, self.manifestFile)
         self._projects[project.name] = project
 
+    for node in config.childNodes:
+      if node.nodeName == 'add-remote':
+        pn = self._reqatt(node, 'to-project')
+        project = self._projects.get(pn)
+        if not project:
+          raise ManifestParseError, \
+                'project %s not defined in %s' % \
+                (pn, self.manifestFile)
+        self._ParseProjectExtraRemote(project, node)
+
   def _AddMetaProjectMirror(self, m):
     name = None
     m_url = m.GetRemote(m.remote.name).url
@@ -281,18 +291,21 @@ class Manifest(object):
 
     for n in node.childNodes:
       if n.nodeName == 'remote':
-        r = self._ParseRemote(n)
-        if project.extraRemotes.get(r.name) \
-           or project.remote.name == r.name:
-          raise ManifestParseError, \
-                'duplicate remote %s in project %s in %s' % \
-                (r.name, project.name, self.manifestFile)
-        project.extraRemotes[r.name] = r
+        self._ParseProjectExtraRemote(project, n)
       elif n.nodeName == 'copyfile':
         self._ParseCopyFile(project, n)
 
     return project
 
+  def _ParseProjectExtraRemote(self, project, n):
+    r = self._ParseRemote(n)
+    if project.extraRemotes.get(r.name) \
+       or project.remote.name == r.name:
+      raise ManifestParseError, \
+            'duplicate remote %s in project %s in %s' % \
+            (r.name, project.name, self.manifestFile)
+    project.extraRemotes[r.name] = r
+
   def _ParseCopyFile(self, project, node):
     src = self._reqatt(node, 'src')
     dest = self._reqatt(node, 'dest')