windows: force specified path to be audited in localpath form pathauditor is invoked not only for localpath form using "os.sep" as separator, but also for normalized form using "/": for example, hg internal path like "store/data" under ".hg", or ones normalized by match object this causes insufficient repository nesting check, because current pathauditor implementation divides specified path into components by "os.sep", and this causes to treat multiple path components joined by "/" as single one on Windows environment. this patch applies "util.localpath()" on specified path to force it to be divided into components correctly. in fact, root for pathauditor also uses multiple path separator on Windows. but this does not affect audit itself, so "util.localpath()" is not applied on it.

icasefs: rewrite comment to explain situtation precisely

icasefs: follow standard cache look up pattern

icasefs: disuse length check against un-normcase()-ed filenames this patch disuses length check against un-normcase()-ed filenames gotten by "os.listdir()", because there is no assurance that filesystem stores filenames normalized except in letter case, even though some case insensitive filesystems (in some environment, for some language setting) store them in such manner.