tests/test-filelog.py.out

merge: apply non-interactive working dir updates in parallel

This has a big effect on the performance of working dir updates.

Here are the results of update from null to the given rev in several
repos, on a Linux 3.2 system with 32 cores running ext4, with the progress
extension enabled.

repo             rev           plain  parallel   speedup
hg               7068089c95a2    0.9       0.3       3
mozilla-central  fe1600b22c77   42.8       7.7       5.5
linux-2.6        9ef4b770e069   31.4       4.9       6.4

ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.