Warn instead of crashing because of invalid path in MANIFEST.in (#8286).

sdist used to crash with a full traceback dump instead of printing a
nice warning with the faulty line number.

Lib/distutils/tests/test_sdist.py

@@ -15,6 +15,7 @@ from distutils.tests.test_config import PyPIRCCommandTestCase
 from distutils.errors import DistutilsOptionError
 from distutils.spawn import find_executable
 from distutils.log import WARN
+from distutils.filelist import FileList
 from distutils.archive_util import ARCHIVE_FORMATS
 
 SETUP_PY = """
@@ -265,7 +266,6 @@ class SDistTestCase(PyPIRCCommandTestCase):
         self.assertEqual(len(output), num_formats)
 
     def test_finalize_options(self):
-
         dist, cmd = self.get_cmd()
         cmd.finalize_options()
 
@@ -285,6 +285,32 @@ class SDistTestCase(PyPIRCCommandTestCase):
         cmd.formats = 'supazipa'
         self.assertRaises(DistutilsOptionError, cmd.finalize_options)
 
+    # the following tests make sure there is a nice error message instead
+    # of a traceback when parsing an invalid manifest template
+
+    def _test_template(self, content):
+        dist, cmd = self.get_cmd()
+        os.chdir(self.tmp_dir)
+        self.write_file('MANIFEST.in', content)
+        cmd.ensure_finalized()
+        cmd.filelist = FileList()
+        cmd.read_template()
+        warnings = self.get_logs(WARN)
+        self.assertEqual(len(warnings), 1)
+
+    def test_invalid_template_unknown_command(self):
+        self._test_template('taunt knights *')
+
+    def test_invalid_template_wrong_arguments(self):
+        # this manifest command takes one argument
+        self._test_template('prune')
+
+    @unittest.skipIf(os.name != 'nt', 'test relevant for Windows only')
+    def test_invalid_template_wrong_path(self):
+        # on Windows, trailing slashes are not allowed
+        # this used to crash instead of raising a warning: #8286
+        self._test_template('include examples/')
+
     @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_get_file_list(self):
         # make sure MANIFEST is recalculated