filemerge: move 'merging' output to before file creation

This has no visible impact but makes some future work simpler.

mercurial/filemerge.py

@@ -493,6 +493,13 b' def filemerge(repo, mynode, orig, fcd, f'
         if mergetype == nomerge:
             return func(repo, mynode, orig, fcd, fco, fca, toolconf)
 
+        if orig != fco.path():
+            ui.status(_("merging %s and %s to %s\n") % (orig, fco.path(), fd))
+        else:
+            ui.status(_("merging %s\n") % fd)
+
+        ui.debug("my %s other %s ancestor %s\n" % (fcd, fco, fca))
+
         a = repo.wjoin(fd)
         b = temp("base", fca)
         c = temp("other", fco)
@@ -500,13 +507,6 b' def filemerge(repo, mynode, orig, fcd, f'
         util.copyfile(a, back)
         files = (a, b, c, back)
 
-        if orig != fco.path():
-            ui.status(_("merging %s and %s to %s\n") % (orig, fco.path(), fd))
-        else:
-            ui.status(_("merging %s\n") % fd)
-
-        ui.debug("my %s other %s ancestor %s\n" % (fcd, fco, fca))
-
         r = 0
         if precheck and not precheck(repo, mynode, orig, fcd, fco, fca,
                                      toolconf):