The three replace calls are slower than this simple __contains__,
and anyway we should not have this many paths ending with .i, .d, or .hg
compared to the normal, un-encoded other paths.
Newly added fncache entries were not added to the in-memory cache,
making it possible for 'hg convert' to cause duplicates in
.hg/store/fncache.
Duplicates in the fncache file are harmless, but excessive numbers
of duplicates from large converted repositories may slow down
execution speed considerably.
the escaping of directories ending with .i or .d doesn't
really belong to filelog.
we put the encoding/decoding in store instead, for backwards
compat, streamclone and the fncache file format still uses the
partially encoded filenames.
Windows won't create directories with names ending in period or space, so
we encode the last period/space character in directory names of non-hashed
paths in the store using reversible ~xx encoding (' ' -> '~20', '.' -> '~2e').
With this change it is possible to remove a directory ending in period or space
that was inadvertantly checked in on a linux system while still being able
to clone such a repository with its full history to Windows (see also issue793).
Windows won't create directories with names ending in period or space, so
we replace the last period/space character in truncated directory names of
hashed paths with some other character (underbar).
* adds a new entry 'fncache' to '.hg/requires' for new repos
* writes new file '.hg/store/fncache'
* hash-encodes filenames with long paths (issue839)
* encodes Windows reserved filenames (issue793)
