build: fix git command

Sam Kleinman · Sam Kleinman · commit e384291281ef · 2015-02-26T09:48:06.000-05:00
diff --git a/.mci.yml b/.mci.yml
@@ -15,7 +15,7 @@ pre:
         ${venv}/pip install -r requirements.txt
 
         # make the current branch always be master.
-        git branch -Df master || true
+        git branch -D master || true
         git checkout -b master origin/master
 
 tasks:
