tags: support 'instant' tag retrieval (
issue548)
- modify _readtagcache() and _writetagcache() to read/write tag->node
mapping for global tags
- if (and only if) tip unchanged, use that cached mapping to avoid
reading any revisions of .hgtags
- change so tag names are UTF-8 in memory in tags.py, and converted to
local encoding as late as possible (in localrepository._findtags())
tags: implement persistent tag caching (
issue548).
- rename findglobaltags() to findglobaltags1() (so the "no cache"
implementation is still there if we need it)
- add findglobaltags2() and make findglobaltags() an alias for it
(disabling tag caching is a one-line patch)
- factor out tagcache class with methods readcache() and writecache();
the expensive part of tag finding (iterate over heads and find
.hgtags filenode) is now in tagcache.readcache()
localrepo: add destroyed() method for strip/rollback to use (
issue548).