Fix typo

mdboom · mdboom · commit 2e0613a4cd69 · 2016-07-19T14:59:32.000-04:00
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -2580,7 +2580,7 @@ def _putmask(a, mask, values):
 LOCKERROR: matplotlib is trying to acquire the lock
     {!r}
 and has failed.  This maybe due to any other process holding this
-lock.  If you are sure no other matplotlib process in running try
+lock.  If you are sure no other matplotlib process is running try
 removing these folders and trying again.
 """
 
