gh-91276: revert the increase of dis output width (GH-92126)

Lib/dis.py

@@ -264,7 +264,7 @@ def show_code(co, *, file=None):
 _ExceptionTableEntry = collections.namedtuple("_ExceptionTableEntry",
     "start end target depth lasti")
 
-_OPNAME_WIDTH = max(map(len, opmap))
+_OPNAME_WIDTH = 20
 _OPARG_WIDTH = 5
 
 class Instruction(_Instruction):

Lib/test/test_dis.py

@@ -734,7 +734,19 @@ def test_boundaries(self):
         self.assertEqual(dis.opmap["STORE_NAME"], dis.HAVE_ARGUMENT)
 
     def test_widths(self):
+        long_opcodes = set(['POP_JUMP_FORWARD_IF_FALSE',
+                            'POP_JUMP_FORWARD_IF_TRUE',
+                            'POP_JUMP_FORWARD_IF_NOT_NONE',
+                            'POP_JUMP_FORWARD_IF_NONE',
+                            'POP_JUMP_BACKWARD_IF_FALSE',
+                            'POP_JUMP_BACKWARD_IF_TRUE',
+                            'POP_JUMP_BACKWARD_IF_NOT_NONE',
+                            'POP_JUMP_BACKWARD_IF_NONE',
+                            'JUMP_BACKWARD_NO_INTERRUPT',
+                           ])
         for opcode, opname in enumerate(dis.opname):
+            if opname in long_opcodes:
+                continue
             with self.subTest(opname=opname):
                 width = dis._OPNAME_WIDTH
                 if opcode < dis.HAVE_ARGUMENT: