--- a/mercurial/sparse.py	Thu Jul 06 12:26:04 2017 -0700
+++ b/mercurial/sparse.py	Thu Jul 06 12:20:53 2017 -0700
@@ -126,3 +126,6 @@
         profiles.update(patternsforrev(repo, rev)[2])
 
     return profiles
+
+def invalidatesignaturecache(repo):
+    repo._sparsesignaturecache.clear()