make `test/setup.sh` work under go 1.5
make `test/setup.sh` work under go 1.5

Fixes #1543.

rade/weave,aaam/weave,aaam/weave,squaremo/weave,awh/weave,n054/weave,paulbellamy/weave,bboreham/weave,rade/weave,bboreham/weave,tomwilkie/weave,rade/weave,dpw/weave,rade/weave,awh/weave,aaam/weave,tomwilkie/weave,n054/weave,bboreham/weave,awh/weave,squaremo/weave,aaam/weave,paulbellamy/weave,tomwilkie/weave,aaam/weave,tomwilkie/weave,rade/weave,paulbellamy/weave,weaveworks/weave,dpw/weave,bboreham/weave,tomwilkie/weave,squaremo/weave,weaveworks/weave,paulbellamy/weave,squaremo/weave,dpw/weave,weaveworks/weave,n054/weave,awh/weave,dpw/weave,bboreham/weave,squaremo/weave,n054/weave,awh/weave,dpw/weave,weaveworks/weave,n054/weave