We have a JIRA issue with unique key: MAGMA-1

When a commit comment contains this:
"Merging branch magma-1.0.x"

The JIRA plugin will associate that commit to MAGMA-1.

This is probably use to allow comments such as:
"Fixed MAGMA-1."
to work.

The regular expression should be a bit more restrictive: require a whitespace or EOF after the dot.