Fixed a bug that one or two people had mentioned years ago, but I was never
able to reproduce myself or get anyone to reproduce in a useful way. It
caused log files that were supposed to be committed to the git-annex branch
to end up in master. Turned out to involve weird stuff when the environment
contains two different settings for a single variable. So was easily fixed
at last. (I'm pretty sure the code would have never had this bug if
Data.AssocList was not buried inside an xml library, which rather
discourages using it when dealing with the environment.)

Also worked on, and hopefully fixed, another OSX cpu optimisations problem.
This one involving shared libraries that git-annex uses for XMPP.

Also made the assistant detect corrupt .git/annex/index files on startup
and remove them. It was already able to recover from corrupt .git/index
files.

Today's work was sponsored by David Wagner.
