--- a/mercurial/match.py	Mon May 22 19:29:21 2017 +0200
+++ b/mercurial/match.py	Mon May 22 08:49:34 2017 -0700
@@ -120,6 +120,9 @@
     """
     normalize = _donormalize
     if icasefs:
+        if exact:
+            raise error.Abort(_("a case-insensitive exact matcher doesn't "
+                                "make sense"))
         dirstate = ctx.repo().dirstate
         dsnormalize = dirstate.normalize