Changing unknown flags on GET to raise ValueError.

ChangeLog

@@ -1,3 +1,6 @@
+   *  If unknown flags in get request, raises a value error rather than the
+      code bombing out.
+
    *  Setting the SERVER_MAX_* values after import did not work, despite
       being documented to.  Reported by alexf101 on github.
 

memcache.py

@@ -1033,6 +1033,7 @@ class Client(local):
                 return None
         else:
             self.debuglog("unknown flags on get: %x\n" % flags)
+            raise ValueError('Unknown flags on get: %x' % flags)
 
         return val