Issue #24669: Fix inspect.getsource() for 'async def' functions.

Patch by Kai Groner.
diff --git a/Lib/inspect.py b/Lib/inspect.py
index 42f24cd..4c1ac1f 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -798,7 +798,7 @@
         if not hasattr(object, 'co_firstlineno'):
             raise OSError('could not find function definition')
         lnum = object.co_firstlineno - 1
-        pat = re.compile(r'^(\s*def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
+        pat = re.compile(r'^(\s*def\s)|(\s*async\s+def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
         while lnum > 0:
             if pat.match(lines[lnum]): break
             lnum = lnum - 1
diff --git a/Lib/test/inspect_fodder.py b/Lib/test/inspect_fodder.py
index 6f0cad9..068d825 100644
--- a/Lib/test/inspect_fodder.py
+++ b/Lib/test/inspect_fodder.py
@@ -66,3 +66,6 @@
         pass
     def contradiction(self):
         pass
+
+async def lobbest(grenade):
+    pass
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 8e0e73c..e620893 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -336,6 +336,7 @@
     def test_getfunctions(self):
         functions = inspect.getmembers(mod, inspect.isfunction)
         self.assertEqual(functions, [('eggs', mod.eggs),
+                                     ('lobbest', mod.lobbest),
                                      ('spam', mod.spam)])
 
     @unittest.skipIf(sys.flags.optimize >= 2,
@@ -393,6 +394,7 @@
     def test_getsource(self):
         self.assertSourceEqual(git.abuse, 29, 39)
         self.assertSourceEqual(mod.StupidGit, 21, 50)
+        self.assertSourceEqual(mod.lobbest, 70, 71)
 
     def test_getsourcefile(self):
         self.assertEqual(normcase(inspect.getsourcefile(mod.spam)), modfile)