Add branch information to hg export.

mercurial/patch.py

@@ -612,6 +612,7 b" def export(repo, revs, template='hg-%h.p"
         ctx = repo.changectx(rev)
         node = ctx.node()
         parents = [p.node() for p in ctx.parents() if p]
+        branch = ctx.branch()
         if switch_parent:
             parents.reverse()
         prev = (parents and parents[0]) or nullid
@@ -625,6 +626,8 b" def export(repo, revs, template='hg-%h.p"
         fp.write("# HG changeset patch\n")
         fp.write("# User %s\n" % ctx.user())
         fp.write("# Date %d %d\n" % ctx.date())
+        if branch and (branch != 'default'):
+            fp.write("# Branch %s\n" % branch)
         fp.write("# Node ID %s\n" % hex(node))
         fp.write("# Parent  %s\n" % hex(prev))
         if len(parents) > 1: