merge with stable

mq: examine "pushable" of already applied patch correctly Before this patch, "hg qselect" with --pop/--reapply may pop patches unexpectedly, even when all of patches applied before "qselect" are still pushable. Strictly speaking about the condition of this issue: - before "qselect" - there are N applied patches - the index of the guarded patch X in the series is less than N - after "qselect" - X is still guarded, and - all of applied patched are still pushable In the case above, "hg qselect" should keep current status, but it actually tries to pop patches because of X. The index in "the series" should be used to examine "pushable" of a patch by "mq.pushablek()", but the index in "applied patches" is used, and this may cause unexpected examination of guarded patch. To examine "pushable" of already applied patch correctly, this patch uses "mq.applied[i].name": "pushable" is the function introduced by the previous patch, and it returns "mq.pushable(mq.applied[i].name)[0]".

mq: pop correct patches when changing pushable-ness of already applied ones Before this patch, "hg qselect" with --pop/--reapply may pop incorrect patches, because the index in "applied patches" is used to pop patches by "mq.pop()", even though the index in "the series" should be used. For example, when the already applied patch becomes guarded and it follows the already guarded (= not yet applied) one, "hg qselect" is aborted, because it tries to pop to guarded one. This patch uses "mq.applied[i - 1].name" to pop to the patch, of which the index in the "applied ones" is "i - 1".