--- a/contrib/simplemerge	Thu Feb 10 15:48:01 2022 -0800
+++ b/contrib/simplemerge	Fri Jan 14 08:17:13 2022 -0800
@@ -15,6 +15,7 @@
     fancyopts,
     simplemerge,
     ui as uimod,
+    util,
 )
 from mercurial.utils import procutil, stringutil
 
@@ -116,18 +117,21 @@
     _verifytext(base_input, ui, quiet=quiet, allow_binary=allow_binary)
     _verifytext(other_input, ui, quiet=quiet, allow_binary=allow_binary)
 
-    sys.exit(
-        simplemerge.simplemerge(
-            ui,
-            local_input,
-            base_input,
-            other_input,
-            mode,
-            quiet=True,
-            allow_binary=allow_binary,
-            print_result=opts.get(b'print'),
-        )
+    merged_text, conflicts = simplemerge.simplemerge(
+        ui,
+        local_input,
+        base_input,
+        other_input,
+        mode,
+        quiet=True,
+        allow_binary=allow_binary,
+        print_result=opts.get(b'print'),
     )
+    if opts.get(b'print'):
+        ui.fout.write(merged_text)
+    else:
+        util.writefile(local, merged_text)
+    sys.exit(1 if conflicts else 0)
 except ParseError as e:
     e = stringutil.forcebytestr(e)
     procutil.stdout.write(b"%s: %s\n" % (sys.argv[0].encode('utf8'), e))

--- a/mercurial/filemerge.py	Thu Feb 10 15:48:01 2022 -0800
+++ b/mercurial/filemerge.py	Fri Jan 14 08:17:13 2022 -0800
@@ -442,10 +442,13 @@
             stringutil.binary(input.text()) for input in (local, base, other)
         ):
             return 1  # continue merging
-        r = simplemerge.simplemerge(
-            ui, local, base, other, quiet=True, mode=mode
+        merged_text, conflicts = simplemerge.simplemerge(
+            ui, local, base, other, mode=mode
         )
-        if not r:
+        # fcd.flags() already has the merged flags (done in
+        # mergestate.resolve())
+        local.fctx.write(merged_text, local.fctx.flags())
+        if not conflicts:
             ui.debug(b" premerge successful\n")
             return 0
         if premerge not in validkeep:
@@ -489,8 +492,14 @@
         _verifytext(other, ui)
     except error.Abort:
         return True, True, False
-    r = simplemerge.simplemerge(ui, local, base, other, mode=mode)
-    return True, r, False
+    else:
+        merged_text, conflicts = simplemerge.simplemerge(
+            ui, local, base, other, mode=mode
+        )
+        # fcd.flags() already has the merged flags (done in
+        # mergestate.resolve())
+        local.fctx.write(merged_text, local.fctx.flags())
+        return True, conflicts, False
 
 
 @internaltool(

--- a/mercurial/simplemerge.py	Thu Feb 10 15:48:01 2022 -0800
+++ b/mercurial/simplemerge.py	Fri Jan 14 08:17:13 2022 -0800
@@ -532,11 +532,4 @@
             lines, conflicts = render_minimized(m3, *labels)
 
     mergedtext = b''.join(lines)
-    if print_result:
-        ui.fout.write(mergedtext)
-    else:
-        # local.fctx.flags() already has the merged flags (done in
-        # mergestate.resolve())
-        local.fctx.write(mergedtext, local.fctx.flags())
-
-    return conflicts
+    return mergedtext, conflicts