fix two-argument gitdiff

diff --git a/pws b/pws
index bc54a4972ed2c7a1217c7b5f7215121b5bfdc492..ca96ed4bc1c18aa7aada37216a1260ad0ee0cedc 100755 (executable)
--- a/pws
+++ b/pws
@@ -916,7 +916,7 @@ class GitDiff
     if ARGV.length == 1
       @commit = 'HEAD'
       @filename = ARGV.shift
-    elsif ARGV.length == 1
+    elsif ARGV.length == 2
       @commit = ARGV.shift
       @filename = ARGV.shift
     else