HG: Commits with no commit message break indexing

This seems to be related to FE-3029 but doesn't appear to be the same (I'm running off default which, I believe, has this fix in it)

I will upload my repo via DropBox and add a link to it in the comments.

Repository index failed due to error com.cenqua.fisheye.rep.RepositoryClientException: com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS: com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS: com.atlassian.utils.process.ProcessException: While executing: "hg --config extensions.felog=/Users/michaelstudman/Projects/fecru-xref-plugin/target/fecru/home/python/hg/hgfelog/hgfelog.py --config ui.verbose=false felog 68869f7d2c5e80947549f92e6b66fa0d1ca53c44 -p -m " com.atlassian.utils.process.ProcessException: java.lang.RuntimeException: Match failed: string [P:737ddf9322e75a6a77e518d0f21c666e28b533bd], pattern [M:(.*)] java.lang.RuntimeException: Match failed: string [P:737ddf9322e75a6a77e518d0f21c666e28b533bd], pattern [M:(.*)]