It seems that the JIRA plugin resolves anything like "\s*-\d*" as a
jira bug number. A common string that fits this pattern is UTF-8,
which likely isn't a jira bug number. We've had a few builds fail because the
plugin failed to add a comment to the non-existent UTF-8 Jira bug
after a successful build.
More generally, perhaps the plugin can distinguish between issues that exist and
issues that don't. In other words, a typo in a commit message
shouldn't cause the build to fail.