Avoid alternation and \U in sed regexps.
Avoid alternation and \U in sed regexps.

R=iant
https://golang.org/cl/3379042

golang/gofrontend,anlhord/gofrontend,anlhord/gofrontend,golang/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,qskycolor/gofrontend,golang/gofrontend,anlhord/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,golang/gofrontend,qskycolor/gofrontend,qskycolor/gofrontend