Merge branch 'av/fsmonitor'

Various fixes to bp/fsmonitor topic.

* av/fsmonitor:
fsmonitor: simplify determining the git worktree under Windows
fsmonitor: store fsmonitor bitmap before splitting index
fsmonitor: read from getcwd(), not the PWD environment variable
fsmonitor: delay updating state until after split index is merged
fsmonitor: document GIT_TRACE_FSMONITOR
fsmonitor: don't bother pretty-printing JSON from watchman
fsmonitor: set the PWD to the top of the working tree

diff --cc Documentation/git.txt
Simple merge

diff --cc cache.h
Simple merge

diff --cc read-cache.c
Simple merge