info: fix "current" output

The "Current revision" field shows the revision as listed in the
manifest.  I think most users expect this to show the revision
that the git tree is checked out to instead.  Switch the output
to show that revision instead, and add a "Current branch" if it
matches a local branch.

Change-Id: Ib546f5ebbc8a23875fbd14bf166fbe95b7dd244e
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/239240
Reviewed-by: David Pursehouse <dpursehouse@collab.net>
Tested-by: Mike Frysinger <vapier@google.com>

subcmds/info.py

@@ -94,13 +94,19 @@ class Info(PagedCommand):
       self.out.nl()
 
       self.heading("Current revision: ")
-      self.headtext(p.revisionExpr)
+      self.headtext(p.GetRevisionId())
       self.out.nl()
 
+      currentBranch = p.CurrentBranch
+      if currentBranch:
+        self.heading('Current branch: ')
+        self.headtext(currentBranch)
+        self.out.nl()
+
       localBranches = list(p.GetBranches().keys())
       self.heading("Local Branches: ")
       self.redtext(str(len(localBranches)))
-      if len(localBranches) > 0:
+      if localBranches:
         self.text(" [")
         self.text(", ".join(localBranches))
         self.text("]")