histedit: save manually edited commit message into ".hg/last-message.txt" Before this patch, manually edited commit message for "message" command in histedit-ing is not saved into ".hg/last-message.txt" until it is saved by "localrepository.savecommitmessage()" in "localrepository.commit()". This may lose such commit message, if unexpected exception is raised. This patch saves manually edited commit message for "message" comand in histedit-ing into ".hg/last-message.txt" just after user editing. This is the simplest implementation to fix on stable. Editing and saving commit message should be centralized into the framework of "localrepository.commit()" with "editor" argument in the future. This patch uses repository wrapping class for exception raising before saving commit message in "localrepository.commit()" easily and certainly, because such exception requires corner case condition.