pathutil: add dirname and join functions This adds dirname and join functions to pathutil which are explicitly for handling '/' delimited paths. The implementations are basically copy paste from python's posix os.path.dirname and os.path.join functions.

changelog: move index_get_parents function up index_get_parents can be used in index_headrevs, to do so it needs to be moved up in the compilation unit.

mergecopies: avoid slowdown from linkrev adjustment (issue4680) checkcopies was using fctx.rev() which it was expecting would be equivalent to linkrev() but was triggering the new _adjustlinkrev path. This was making grafts and merges with large sets of potential copies very expensive.

hgweb: remove an extra call to nodebranchnodefault() in changesetentry() showbranch variable already contains the result of nodebranchnodefault(ctx), so it can be reused.

profile: disable nested report in lsprof by default The nesting makes profiles harder to read and often pushes important data off the end of the report.

manifest: use match.prefix() instead of 'not match.anypats()' It seems clearer to check for what it is than what it isn't.

dirstate: use match.prefix() instead of 'not match.anypats()' It seems clearer to check for what it is than what it isn't.