Fix pylint issue

Travis-ci tests with python3 were failing with:

************* Module manic.repository_svn
R1724:221,12: Unnecessary "else" after "continue" (no-else-continue)

This should fix the problem.

(I'm not sure why this started failing now: this is old code. Maybe
pylint recently was updated to add this check?)

manic/repository_svn.py

@@ -220,9 +220,8 @@ def xml_status_is_dirty(svn_output):
                 continue
             if item == SVN_UNVERSIONED:
                 continue
-            else:
-                is_dirty = True
-                break
+            is_dirty = True
+            break
         return is_dirty
 
     # ----------------------------------------------------------------