ensure go_version segment prints if PWD is subset of non-empty GOPATH

test/segments/go_version.spec

@@ -19,8 +19,11 @@ function testGo() {
   alias go=mockGo
   POWERLEVEL9K_LEFT_PROMPT_ELEMENTS=(go_version)
 
+  PWD="$HOME/go/src/github.com/bhilburn/powerlevel9k"
+
   assertEquals "%K{green} %F{255}go1.5.3 %k%F{green}%f " "$(build_left_prompt)"
 
+  unset PWD
   unset POWERLEVEL9K_LEFT_PROMPT_ELEMENTS
   unalias go
 }