Further refine remote branch tracking in b1ec6e8

Move operations that are dependant on a remote branch under a if
is_remote_branch() conditional.  While at it, remove assignment to cmd
string in same block that wasn't used when calling _run().

git

@@ -197,10 +197,10 @@ def switch_version(module, dest, remote, version):
     os.chdir(dest)
     cmd = ''
     if version != 'HEAD':
-        if not is_local_branch(module, dest, version) and is_remote_branch(module, dest, remote, version):
+        if is_remote_branch(module, dest, remote, version):
+            if not is_local_branch(module, dest, version):
                 cmd = "git checkout --track -b %s %s/%s" % (version, remote, version)
-        elif is_local_branch(module, dest, version):
-            cmd = "git checkout --force %s" % version
+            else:
                 (rc, out, err) = _run("git checkout --force %s" % version)
                 if rc != 0:
                     module.fail_json(msg="Failed to checkout branch %s" % version)