goinstall: don't wrongly error out with "multiple package names"
goinstall: don't wrongly error out with "multiple package names"

Fixes issue 1215.

R=adg, rsc
CC=golang-dev
http://codereview.appspot.com/2695042

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

apparentlymart/golang,apparentlymart/golang,dsriram/golang,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,h8liu/golang,gnanderson/go,ssrl/go,dsriram/golang,h8liu/golang,dsriram/golang,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,tv42/old-go,gnanderson/go,gnanderson/go,pombredanne/go-deleteme,pombredanne/go-deleteme,ssrl/go,pombredanne/go-deleteme,ssrl/go,pombredanne/go-deleteme,h8liu/golang,apparentlymart/golang,tv42/old-go,ssrl/go,ssrl/go,h8liu/golang,dsriram/golang,h8liu/golang,apparentlymart/golang,h8liu/golang,dsriram/golang,gnanderson/go,ssrl/go,h8liu/golang,tv42/old-go,gnanderson/go,ssrl/go,tv42/old-go,apparentlymart/golang,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,apparentlymart/golang