Rename "dir" variables

The variable name "dir" conflicts with the name of a Python built-in
function: http://docs.python.org/library/functions.html#dir

Change-Id: I850f3ec8df7563dc85e21f2876fe5e6550ca2d8f
diff --git a/git_command.py b/git_command.py
index 5988cc2..82709b9 100644
--- a/git_command.py
+++ b/git_command.py
@@ -37,11 +37,11 @@
   if _ssh_sock_path is None:
     if not create:
       return None
-    dir = '/tmp'
-    if not os.path.exists(dir):
-      dir = tempfile.gettempdir()
+    tmp_dir = '/tmp'
+    if not os.path.exists(tmp_dir):
+      tmp_dir = tempfile.gettempdir()
     _ssh_sock_path = os.path.join(
-      tempfile.mkdtemp('', 'ssh-', dir),
+      tempfile.mkdtemp('', 'ssh-', tmp_dir),
       'master-%r@%h:%p')
   return _ssh_sock_path