cmd/go: exit with error when $GOPATH is set to "."

[gopherbot]

by nicksaika:

Running "GOPATH=. go build pkg/foo" should be disallowed when $GOPATH is set
to "." as the compile process usually errors out by saying it cannot find a
particular file, even though that file definitely exists.

Granted, running the command like so "GOPATH=$PWD go build pkg/foo" works
successfully, but perhaps the go tool should notice when $GOPATH is set to "."
and error out.

[rsc]

Comment 1:

Maybe it should disallow any relative $GOPATH entry.

[gopherbot]

Comment 2 by nicksaika:

That would be good; my thinking is if relative paths in $GOPATH cause the compile
process to fail, why not notice the error before-hand, and gracefully error out?

[rsc]

Comment 3:

Labels changed: added priority-later, removed priority-triage.

Status changed to Accepted.

[rsc]

Comment 4:

Labels changed: added go1.1.

[robpike]

Comment 6:

This issue was closed by revision 916ccbf.

Status changed to Fixed.