cmd/coordinator: fix another UI issue with trybots against old Go releases
cmd/coordinator: fix another UI issue with trybots against old Go releases

Updates golang/go#28580
Updates golang/go#17626

Change-Id: Ifa88e4ad23e823e5d1a25c46b76afb11b4e7907b
Reviewed-on: https://go-review.googlesource.com/c/147497
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>

golang/build,golang/build,golang/build,golang/build