sparse: apply update with in a `parentchange` context

We are changing the reference so we should be within such context manager.

This seems make the actual dirstate content a bit flaky with content being
sometime ambigous (but maybe it was flaky before?)

So I increased the matching.

Differential Revision: https://phab.mercurial-scm.org/D11150

mercurial/sparse.py

@@ -439,13 +439,21 b' def filterupdatesactions(repo, wctx, mct'
                     message,
                 )
 
-        mergemod.applyupdates(
-            repo, tmresult, repo[None], repo[b'.'], False, wantfiledata=False
-        )
+        with repo.dirstate.parentchange():
+            mergemod.applyupdates(
+                repo,
+                tmresult,
+                repo[None],
+                repo[b'.'],
+                False,
+                wantfiledata=False,
+            )
 
-        dirstate = repo.dirstate
-        for file, flags, msg in tmresult.getactions([mergestatemod.ACTION_GET]):
-            dirstate.normal(file)
+            dirstate = repo.dirstate
+            for file, flags, msg in tmresult.getactions(
+                [mergestatemod.ACTION_GET]
+            ):
+                dirstate.normal(file)
 
     profiles = activeconfig(repo)[2]
     changedprofiles = profiles & files

tests/test-sparse.t

@@ -420,12 +420,12 b' manifest'
 We have files in the dirstate that are included and excluded. Some are in the
 manifest and some are not.
   $ hg debugdirstate --no-dates
-  n 644          0 * excluded (glob)
-  a   0         -1 * excludednomanifest (glob)
-  n 644          0 * included (glob)
-  a   0         -1 * includedadded (glob)
+  n * excluded (glob)
+  a * excludednomanifest (glob)
+  n * included (glob)
+  a * includedadded (glob)
   $ hg debugrebuilddirstate --minimal
   $ hg debugdirstate --no-dates
-  n 644          0 * included (glob)
-  a   0         -1 * includedadded (glob)
+  n * included (glob)
+  a * includedadded (glob)