remove the unprotected key name from create.py

Small fix to use dicts correctly.

lib/spack/spack/cmd/create.py

@@ -222,7 +222,7 @@ def fetch_tarballs(url, name, args):
     archives_to_fetch = 1
     if not versions:
         # If the fetch failed for some reason, revert to what the user provided
-        versions = { version : url }
+        versions = { "version" : url }
     elif len(versions) > 1:
         tty.msg("Found %s versions of %s:" % (len(versions), name),
                 *spack.cmd.elide_list(