don't exec git

Index: dist/nimble/src/nimblepkg/options.nim
--- dist/nimble/src/nimblepkg/options.nim.orig
+++ dist/nimble/src/nimblepkg/options.nim
@@ -161,12 +161,6 @@ proc writeHelp*(quit=true) =
 proc writeVersion*() =
   echo("nimble v$# compiled at $# $#" %
       [nimbleVersion, CompileDate, CompileTime])
-  const execResult = gorgeEx("git rev-parse HEAD")
-  when execResult[0].len > 0 and execResult[1] == QuitSuccess:
-    echo "git hash: ", execResult[0]
-  else:
-    {.warning: "Couldn't determine GIT hash: " & execResult[0].}
-    echo "git hash: couldn't determine git hash"
   raise NimbleQuit(msg: "")
 
 proc parseActionType*(action: string): ActionType =
