icasefs: ignore removed files at building "dirstate._foldmap" up on icasefs Before this patch, all files in dirstate are used to build "_foldmap" up on case insensitive filesystem regardless of their statuses. For example, when dirstate contains both removed file 'a' and added file 'A', "_foldmap" may be updated finally by removed file 'a'. This causes unexpected status information for added file 'A' at "hg status" invocation. This patch ignores removed files at building "_foldmap" up on case insensitive filessytem. This patch doesn't add any test, because this issue is difficult to reproduce intentionally: it depends on iteration order of "dirstate._map".