update: move check for dirty wdir into hg.updatetotally()

The function has a "check" parameter that's currently unused, and it
makes sense to me to have it honor it. That way other callers than
commands.update() could set it if they needed.

mercurial/commands.py

@@ -5363,9 +5363,6 b' def update(ui, repo, node=None, rev=None'
         brev = rev
         rev = scmutil.revsingle(repo, rev, rev).rev()
 
-        if check:
-            cmdutil.bailifchanged(repo, merge=False)
-
         repo.ui.setconfig('ui', 'forcemerge', tool, 'update')
 
         return hg.updatetotally(ui, repo, rev, brev, clean=clean, check=check)

mercurial/hg.py

@@ -739,6 +739,8 b' def updatetotally(ui, repo, checkout, br'
         if clean:
             ret = _clean(repo, checkout)
         else:
+            if check:
+                cmdutil.bailifchanged(repo, merge=False)
             ret = _update(repo, checkout)
 
         if not ret and movemarkfrom: