make hg mail more forgiving: create CL first, even if gofmt is needed or no reviewers listed.
make hg mail more forgiving:
create CL first, even if gofmt is needed
or no reviewers listed.

R=r
http://go/go-review/1025025

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go