cmd/go: go help mod prints unclear error message on bad mod subcommand #33153
Description
$ go version
go version devel +0cadf40f4c Tue Jul 16 22:31:35 2019 +0000 windows/amd64
go help mod prints:
Go mod provides access to operations on modules.
[...]
Use "go help mod <command>" for more information about a command.
go help mod <command> works as advertised, except when <command> is not a valid mod command; in that case this bizarre error message is printed:
$ go help mod bad
go help mod bad: unknown help topic. Run ' mod'.
It's not clear what it means by Run ' mod', but it doesn't look right.