dirstate: avoid normalizing letter case on icasefs for exact match (issue3340) on icasefs, "hg qnew" fails to import changing letter case of filename already occurred in working directory, for example: $ hg rename a tmp $ hg rename tmp A $ hg qnew casechange $ hg status R a $ "hg qnew" invokes 'dirstate.walk()' via 'localrepository.commit()' with 'exact match' matching object having exact filenames of targets in ones 'files()'. current implementation of 'dirstate.walk()' always normalizes letter case of filenames from 'match.files()' on icasefs, even though exact matching is required. then, files only different in letter case are treated as one file. this patch prevents 'dirstate.walk()' from normalizing, if exact matching is required, even on icasefs. filenames for 'exact matching' are given not from user command line, but from dirstate walk result, manifest of changecontext, patch files or fixed list for specific system files (e.g.: '.hgtags'). in such case, case normalization should not be done, so this patch works well.

i18n-ja: synchronized with cb17c2f5b7b4