largefiles: move "updatestandin" invocation to "hg.updaterepo" wrapper Code paths below expect "hg.updaterepo" (or "hg.update" using it) to execute linear merging: - "update" in commands - "postincoming" in commands, used for: - "hg pull --update" - "hg unbundle --update" - "hgsubrepo.get" in subrepo For linear merging with largefiles, standins should be updated according to (possibly dirty) largefiles before "merge.update" invocation to detect conflicts correctly. Before this patch, only the "update" command can execute linear merging correctly, because largefiles extension takes care of only it. This patch moves "updatestandin" invocation from "overrideupdate" ("hg update" wrapper) to "_hgupdaterepo" ("hg.updaterepo" wrapper) to execute linear merging in "hg.updaterepo" correctly. This is also a preparation to centralize the logic of updating largefiles in the working directory into the function wrapping "merge.update" in the subsequent patch.