When writing manifest, set the dest-branch attribute for projects

When generating a revision locked manifest, we need to know what
ref to push changes to when doing 'repo upload'.  This information
is lost when we lock the revision attribute to a particular commit
hash, so we need to expose it through the dest-branch attribute.

Bug: https://crbug.com/1005103
Test: manual execution
Change-Id: Ib31fd77ad8c9379759c4181dac1ea97de43eec35
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/263572
Tested-by: Sean McAllister <smcallis@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

manifest_xml.py

@@ -284,7 +284,7 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
   def _ParseGroups(self, groups):
     return [x for x in re.split(r'[,\s]+', groups) if x]
 
-  def Save(self, fd, peg_rev=False, peg_rev_upstream=True, groups=None):
+  def Save(self, fd, peg_rev=False, peg_rev_upstream=True, peg_rev_dest_branch=True, groups=None):
     """Write the current manifest out to the given file descriptor.
     """
     mp = self.manifestProject
@@ -389,6 +389,13 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
             # Only save the origin if the origin is not a sha1, and the default
             # isn't our value
             e.setAttribute('upstream', p.revisionExpr)
+
+        if peg_rev_dest_branch:
+          if p.dest_branch:
+            e.setAttribute('dest-branch', p.dest_branch)
+          elif value != p.revisionExpr:
+            e.setAttribute('dest-branch', p.revisionExpr)
+
       else:
         revision = self.remotes[p.remote.orig_name].revision or d.revisionExpr
         if not revision or revision != p.revisionExpr:

subcmds/manifest.py

@@ -38,7 +38,8 @@ The -r option can be used to generate a manifest file with project
 revisions set to the current commit hash.  These are known as
 "revision locked manifests", as they don't follow a particular branch.
 In this case, the 'upstream' attribute is set to the ref we were on
-when the manifest was generated.
+when the manifest was generated.  The 'dest-branch' attribute is set
+to indicate the remote ref to push changes to via 'repo upload'.
 """
 
   @property
@@ -62,6 +63,11 @@ when the manifest was generated.
                  help='If in -r mode, do not write the upstream field.  '
                  'Only of use if the branch names for a sha1 manifest are '
                  'sensitive.')
+    p.add_option('--suppress-dest-branch', dest='peg_rev_dest_branch',
+                 default=True, action='store_false',
+                 help='If in -r mode, do not write the dest-branch field.  '
+                 'Only of use if the branch names for a sha1 manifest are '
+                 'sensitive.')
     p.add_option('-o', '--output-file',
                  dest='output_file',
                  default='-',
@@ -79,7 +85,8 @@ when the manifest was generated.
       fd = open(opt.output_file, 'w')
     self.manifest.Save(fd,
                        peg_rev=opt.peg_rev,
-                       peg_rev_upstream=opt.peg_rev_upstream)
+                       peg_rev_upstream=opt.peg_rev_upstream,
+                       peg_rev_dest_branch=opt.peg_rev_dest_branch)
     fd.close()
     if opt.output_file != '-':
       print('Saved manifest to %s' % opt.output_file, file=sys.stderr)