codereview: drop Author: line on self-clpatch

Right now if a Go developer makes a patch on one machine
and then clpatches it onto another machine, changes
subsequently made to the description are kept only
locally, under the assumption that you are running
clpatch because someone else wrote the CL, so you
don't have permission to update the web.

This change makes clpatch discard the "this was a
clpatch" information from the metadata when you
clpatch your own CLs from one machine to another.

This should eliminate some confusion (for example
in CL 4314054) but will no doubt introduce other
confusion.

R=golang-dev, r2
CC=golang-dev
https://golang.org/cl/4387041

lib/codereview/codereview.py

@@ -1787,8 +1787,10 @@ def DownloadCL(ui, repo, clname):
 	email = match.group(1)
 
 	# Print warning if email is not in CONTRIBUTORS file.
-	FindContributor(ui, repo, email)
-	cl.copied_from = email
+	him = FindContributor(ui, repo, email)
+	me = FindContributor(ui, repo, None)
+	if him != me:
+		cl.copied_from = email
 
 	return cl, diffdata, ""