--- a/mercurial/commands.py	Sat Jun 27 21:45:20 2020 -0400
+++ b/mercurial/commands.py	Thu Jun 25 13:27:37 2020 -0700
@@ -2982,6 +2982,8 @@
         editform=b'graft', **pycompat.strkwargs(opts)
     )
 
+    cmdutil.check_at_most_one_arg(opts, b'abort', b'stop', b'continue')
+
     cont = False
     if opts.get(b'no_commit'):
         if opts.get(b'edit'):
@@ -3004,13 +3006,6 @@
     graftstate = statemod.cmdstate(repo, b'graftstate')
 
     if opts.get(b'stop'):
-        if opts.get(b'continue'):
-            raise error.Abort(
-                _(b"cannot use '--continue' and '--stop' together")
-            )
-        if opts.get(b'abort'):
-            raise error.Abort(_(b"cannot use '--abort' and '--stop' together"))
-
         if any(
             (
                 opts.get(b'edit'),
@@ -3025,10 +3020,6 @@
             raise error.Abort(_(b"cannot specify any other flag with '--stop'"))
         return _stopgraft(ui, repo, graftstate)
     elif opts.get(b'abort'):
-        if opts.get(b'continue'):
-            raise error.Abort(
-                _(b"cannot use '--continue' and '--abort' together")
-            )
         if any(
             (
                 opts.get(b'edit'),

--- a/tests/test-graft-interrupted.t	Sat Jun 27 21:45:20 2020 -0400
+++ b/tests/test-graft-interrupted.t	Thu Jun 25 13:27:37 2020 -0700
@@ -249,7 +249,7 @@
   [1]
 
   $ hg graft --stop --continue
-  abort: cannot use '--continue' and '--stop' together
+  abort: cannot specify both --stop and --continue
   [255]
 
   $ hg graft --stop -U
@@ -355,11 +355,11 @@
   [1]
 
   $ hg graft --continue --abort
-  abort: cannot use '--continue' and '--abort' together
+  abort: cannot specify both --abort and --continue
   [255]
 
   $ hg graft --abort --stop
-  abort: cannot use '--abort' and '--stop' together
+  abort: cannot specify both --abort and --stop
   [255]
 
   $ hg graft --abort --currentuser