status: process `from_p2` file the same as `merged` one

What matters here is that the file constains information coming from the second
parent and should be considered `modified` on plain `hg status.

So we can process `from_p2` file sooner. It also highlight that we probably
don't need the merged/from_p2 distinction at higher level.

Differential Revision: https://phab.mercurial-scm.org/D11591

mercurial/dirstate.py

@@ -1372,7 +1372,7 b' class dirstate(object):'
 
             if not st and t.tracked:
                 dadd(fn)
-            elif t.merged:
+            elif t.merged or t.from_p2:
                 madd(fn)
             elif t.added:
                 aadd(fn)
@@ -1385,7 +1385,6 b' class dirstate(object):'
                         (size != st.st_size and size != st.st_size & _rangemask)
                         or ((mode ^ st.st_mode) & 0o100 and checkexec)
                     )
-                    or t.from_p2
                     or fn in copymap
                 ):
                     if stat.S_ISLNK(st.st_mode) and size != st.st_size: