Description of problem:

When the "pattern" property of a rule contains a Regex with the following structure, the analyzer is unable to parse it and the rule is ignored.

(?P<something> 

Version-Release number of selected component (if applicable): upstream 

How reproducible: Always 

Steps to Reproduce:
1. Execute an analysis using kantra
2. Inspect the analysis log

Actual results:

 There are multiple log lines containing the following error for different rules

level=error msg="unable to get custom variables" error="error parsing regexp: invalid named capture: `(?P<method-names>`" logger=parser ruleID=the-rule-id

Expected results:

The analyzer should be able to parse the rule correctly. 

Additional info:

Attached you'll find an analysis log

This bug could be the cause of https://issues.redhat.com/browse/MTA-1313