Percona Clustercheck Improved Error Handling Patch

Here’s my Github pull request for improved error handling in Percona’s clustercheck utility, used by haproxy for health-checking a Percona XtraDB Cluster.

It adds two features:

1. 401 Unauthorized response for failed authentication
2. 404 Not Found response if the mysql program can’t be found

The error detection is done in a low-latency manner using PIPESTATUS, without an additional database connection. Here is colored diff output.