[#3198] ignore errors when regenerating hashes

The script complains about hashes missing, but that is only temporary until they
are regenerated. A second call to check-hashes.sh will now properly check them
at the end.

Author: andrei-pavel

src/share/yang/modules/utils/bump-up-revisions.sh

@@ -72,4 +72,7 @@ done
 
 # Regenerate hashes.
 rm hashes/*
-./utils/check-hashes.sh -a
+./utils/check-hashes.sh -a 2> /dev/null || true
+
+# Check hashes were regenerated succesfully.
+./utils/check-hashes.sh