windows: use normalized path to check repository nesting current "localrepository._checknested()" uses specified path itself to compare against subrepo pathes. it is invoked from "hgsubrepo.subrepo()" or pathauditor (as callback), and both use "os.sep" as separator. this causes unexpected nesting check result, if subrepo configuration uses "/" as path separator for sub repo path. this path uses "/" to join path components (or apply "util.pconvert()" on path) to normalize.

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