LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/102040045

LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews
https://golang.org/cl/93420046

Fixes #7412.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/92850043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/60640052

The branchtags method was removed but we should've
been using branchmap all along.

http://selenic.com/hg/rev/4274eda143cb

LGTM=franciscossouza, r
R=golang-codereviews, franciscossouza, r
CC=golang-codereviews
https://golang.org/cl/57500045

This seems to be what causes the 'chunk mismatch' errors.
I don't know why the server tells us there's nothing to upload,
but at the least we can warn that it did, so that the user
will try again.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/62840043

LGTM=gri
R=golang-codereviews, gri
CC=golang-codereviews
https://golang.org/cl/61610043

The R= is populated by Rietveld, so it's basically
anyone who replied to the CL. The LGTM= is meant
to record who actually signed off on the CL.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/55390043

See this thread for background:
https://groups.google.com/forum/#!topic/golang-dev/xG7vPi21r8g

R=golang-codereviews, gobot, golang-dev, dsymonds
CC=golang-codereviews, golang-dev
https://golang.org/cl/44450043

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/15360045