Log Message:
Update Go to 1.7.3.

go1.7.2 should not be used. It was tagged but not fully released. The release
was deferred due to a last minute bug report. Use go1.7.3 instead, and refer to
the summary of changes below.

go1.7.3 (released 2016/10/19) includes fixes to the compiler, runtime, and the
crypto/cipher, crypto/tls, net/http, and strings packages. See the Go 1.7.3
milestone on our issue tracker for details.