Wrote some evil code you don't want to run today. Git.Destroyer randomly
generates Damage, and applies it to a git repository, in a way that is
reproducible -- applying the same Damage to clones of the same git repo 
will always yeild the same result.

This let me build a test harness for git-repair, which repeatedly clones,
damages, and repairs a repository. And when it fails, I can just ask it to
retry after fixing the bug and it'll re-run every attempt it's logged.

This is already yeilding improvements to the git-repair code.
The first randomly constructed Damage that it failed to recover
turned out to be a truncated index file that hid some other
corrupted object files from being repaired.

	[Damage Empty (FileSelector 1),
	 Damage Empty (FileSelector 2),
	 Damage Empty (FileSelector 3),
	 Damage Reverse (FileSelector 3),
	 Damage (ScrambleFileMode 3) (FileSelector 5),
	 Damage Delete (FileSelector 9),
	 Damage (PrependGarbage "¥SOH¥STX¥ENQ¥f¥a¥ACK¥b¥DLE¥n") (FileSelector 9),
	 Damage Empty (FileSelector 12),
	 Damage (CorruptByte 11 25) (FileSelector 6),
	 Damage Empty (FileSelector 5),
	 Damage (ScrambleFileMode 4294967281) (FileSelector 14)
	]

I need to improve the ranges of files that it damages -- currently QuickCheck
seems to only be selecting one of the first 20 or so files. Also, it's quite
common that it will damage `.git/config` so badly that git thinks it's not
a git repository anymore. I am not sure if that is something `git-repair`
should try to deal with.

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Today's work was sponsored by the WikiMedia Foundation.