dirstate: do no use `set_clean` in revert

dirstate: do no use `set_clean` in revert

The current `set_clean` usage is racy (the file might be modified between its
restoration and the `set_clean` call).

So we simply leave the file as ambiguous and the next status will fix that.

We still have to make sure the copy information is dropped, so we teach dirstate
how to do that.

The win32txt extension is confused after this because current logic is broken in
more location. However this series will ultimately fix that so we "ignore" it
for now. Fixing it now is complicated without some extra fix landing later.

Differential Revision: https://phab.mercurial-scm.org/D11788

--- a/mercurial/cmdutil.py	Thu Nov 18 22:49:05 2021 +0100
+++ b/mercurial/cmdutil.py	Mon Nov 22 15:58:51 2021 +0100
@@ -3646,15 +3646,14 @@
         prntstatusmsg(b'drop', f)
         repo.dirstate.set_untracked(f)
 
-    normal = None
-    if node == parent:
-        # We're reverting to our parent. If possible, we'd like status
-        # to report the file as clean. We have to use normallookup for
-        # merges to avoid losing information about merged/dirty files.
-        if p2 != repo.nullid:
-            normal = repo.dirstate.set_tracked
-        else:
-            normal = repo.dirstate.set_clean
+    # We are reverting to our parent. If possible, we had like `hg status`
+    # to report the file as clean. We have to be less agressive for
+    # merges to avoid losing information about copy introduced by the merge.
+    # This might comes with bugs ?
+    reset_copy = p2 == repo.nullid
+
+    def normal(filename):
+        return repo.dirstate.set_tracked(filename, reset_copy=reset_copy)
 
     newlyaddedandmodifiedfiles = set()
     if interactive:
@@ -3749,9 +3748,6 @@
             checkout(f)
             repo.dirstate.set_tracked(f)
 
-    normal = repo.dirstate.set_tracked
-    if node == parent and p2 == repo.nullid:
-        normal = repo.dirstate.set_clean
     for f in actions[b'undelete'][0]:
         if interactive:
             choice = repo.ui.promptchoice(

--- a/mercurial/dirstate.py	Thu Nov 18 22:49:05 2021 +0100
+++ b/mercurial/dirstate.py	Mon Nov 22 15:58:51 2021 +0100
@@ -452,19 +452,24 @@
         return self._map.copymap
 
     @requires_no_parents_change
-    def set_tracked(self, filename):
+    def set_tracked(self, filename, reset_copy=False):
         """a "public" method for generic code to mark a file as tracked
 
         This function is to be called outside of "update/merge" case. For
         example by a command like `hg add X`.
 
+        if reset_copy is set, any existing copy information will be dropped.
+
         return True the file was previously untracked, False otherwise.
         """
         self._dirty = True
         entry = self._map.get(filename)
         if entry is None or not entry.tracked:
             self._check_new_tracked_filename(filename)
-        return self._map.set_tracked(filename)
+        pre_tracked = self._map.set_tracked(filename)
+        if reset_copy:
+            self._map.copymap.pop(filename, None)
+        return pre_tracked
 
     @requires_no_parents_change
     def set_untracked(self, filename):

--- a/tests/test-revert.t	Thu Nov 18 22:49:05 2021 +0100
+++ b/tests/test-revert.t	Mon Nov 22 15:58:51 2021 +0100
@@ -320,7 +320,7 @@
 
   $ hg mv --force a b/b
   $ hg revert b/b
-  $ hg status a b/b
+  $ hg status a b/b --copies
 
   $ cd ..
 

--- a/tests/test-win32text.t	Thu Nov 18 22:49:05 2021 +0100
+++ b/tests/test-win32text.t	Mon Nov 22 15:58:51 2021 +0100
@@ -418,6 +418,7 @@
   $ hg revert -a
   reverting linefeed
   $ hg st -q
+  M linefeed (known-bad-output !)
   $ cat linefeed
   % just linefeed\r (esc)