dirstate: make sure that status does not overlook the fallback flags

dirstate: make sure that status does not overlook the fallback flags

Without this extra checks, file with fallback flags change as the only change
would be overlooked.

In the future we might store proper data in the dirstate and do less lookup.
However, for now this will do to make sure that 6.0 is forward compatible with
later version.

Differential Revision: https://phab.mercurial-scm.org/D11729

--- a/mercurial/dirstate.py	Thu Oct 28 17:26:03 2021 +0200
+++ b/mercurial/dirstate.py	Thu Oct 28 17:44:58 2021 +0200
@@ -1359,6 +1359,7 @@
         mexact = match.exact
         dirignore = self._dirignore
         checkexec = self._checkexec
+        checklink = self._checklink
         copymap = self._map.copymap
         lastnormaltime = self._lastnormaltime
 
@@ -1391,7 +1392,17 @@
             elif t.removed:
                 radd(fn)
             elif t.tracked:
-                if (
+                if not checklink and t.has_fallback_symlink:
+                    # If the file system does not support symlink, the mode
+                    # might not be correctly stored in the dirstate, so do not
+                    # trust it.
+                    ladd(fn)
+                elif not checkexec and t.has_fallback_exec:
+                    # If the file system does not support exec bits, the mode
+                    # might not be correctly stored in the dirstate, so do not
+                    # trust it.
+                    ladd(fn)
+                elif (
                     size >= 0
                     and (
                         (size != st.st_size and size != st.st_size & _rangemask)

--- a/mercurial/helptext/internals/dirstate-v2.txt	Thu Oct 28 17:26:03 2021 +0200
+++ b/mercurial/helptext/internals/dirstate-v2.txt	Thu Oct 28 17:44:58 2021 +0200
@@ -523,12 +523,18 @@
     this indicates whether the file’s own is expected
     to have execute permission.
 
+    Beware that on system without fs support for this information, the value
+    stored in the dirstate might be wrong and should not be relied on.
+
 `MODE_IS_SYMLINK`
     Must be unset if `HAS_MODE_AND_SIZE` is unset.
     If `HAS_MODE_AND_SIZE` is set,
     this indicates whether the file is expected to be a symlink
     as opposed to a normal file.
 
+    Beware that on system without fs support for this information, the value
+    stored in the dirstate might be wrong and should not be relied on.
+
 `EXPECTED_STATE_IS_MODIFIED`
     Must be unset for untracked nodes.
     For: