merge: remove useless dirstate.normallookup() invocation in applyupdates()

Explicit 'dirstate.normallookup()' invocation via 'dirtysubstate()' in
'applyupdates()' is useless now, because previous patch fixed the
relevant issue by writing in-memory dirstate changes out at the end of
dirty check.

'dirstate.normallookup()' invocation was introduced by 6becb9dbca25 to
avoid occasional test failure. This is partial backout of it (added
tests are still left).

mercurial/merge.py

@@ -741,15 +741,7 b' def applyupdates(repo, actions, wctx, mc'
 
     numupdates = sum(len(l) for m, l in actions.items() if m != 'k')
 
-    def dirtysubstate():
-        # mark '.hgsubstate' as possibly dirty forcibly, because
-        # modified '.hgsubstate' is misunderstood as clean,
-        # when both st_size/st_mtime of '.hgsubstate' aren't changed,
-        # even if "submerge" fails and '.hgsubstate' is inconsistent
-        repo.dirstate.normallookup('.hgsubstate')
-
     if [a for a in actions['r'] if a[0] == '.hgsubstate']:
-        dirtysubstate()
         subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
 
     # remove in parallel (must come first)
@@ -768,7 +760,6 b' def applyupdates(repo, actions, wctx, mc'
     updated = len(actions['g'])
 
     if [a for a in actions['g'] if a[0] == '.hgsubstate']:
-        dirtysubstate()
         subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
 
     # forget (manifest only, just log it) (must come first)
@@ -794,7 +785,6 b' def applyupdates(repo, actions, wctx, mc'
         z += 1
         progress(_updating, z, item=f, total=numupdates, unit=_files)
         if f == '.hgsubstate': # subrepo states need updating
-            dirtysubstate()
             subrepo.submerge(repo, wctx, mctx, wctx.ancestor(mctx),
                              overwrite)
             continue