Fix get_line_code for stubs

jedi/api/__init__.py

@@ -160,7 +160,7 @@ class Script:
         self._module_node, code = self._inference_state.parse_and_get_code(
             code=code,
             path=self.path,
-            use_latest_grammar=path and path.suffix == 'pyi',
+            use_latest_grammar=path and path.suffix == '.pyi',
             cache=False,  # No disk cache, because the current script often changes.
             diff_cache=settings.fast_parser,
             cache_path=settings.cache_directory,

test/test_inference/test_gradual/test_conversion.py

@@ -1,4 +1,5 @@
 import os
+from parso.cache import parser_cache
 
 from test.helpers import root_dir
 from jedi.api.project import Project
@@ -64,6 +65,17 @@ def test_goto_import(Script):
     assert not d.is_stub()
 
 
+def test_stub_get_line_code(Script):
+    code = 'from abc import ABC; ABC'
+    script = Script(code)
+    d, = script.goto(only_stubs=True)
+    assert d.get_line_code() == 'class ABC(metaclass=ABCMeta): ...\n'
+    del parser_cache[script._inference_state.latest_grammar._hashed][str(d.module_path)]
+    d, = Script(path=d.module_path).goto(d.line, d.column, only_stubs=True)
+    assert d.is_stub()
+    assert d.get_line_code() == 'class ABC(metaclass=ABCMeta): ...\n'
+
+
 def test_os_stat_result(Script):
     d, = Script('import os; os.stat_result').goto()
     assert d.is_stub()