#2466: ismount now recognizes mount points user can't access.

Patch by Robin Roth, reviewed by Serhiy Storchaka, comment wording
tweaked by me.
diff --git a/Misc/ACKS b/Misc/ACKS
index 150d37a..0664e87 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1258,6 +1258,7 @@
 Just van Rossum
 Hugo van Rossum
 Saskia van Rossum
+Robin Roth
 Clement Rouault
 Donald Wallace Rouse II
 Liam Routt