gh-103088: fix activate script not working in Cygwin

.gitattributes

@@ -32,6 +32,9 @@ Lib/test/test_importlib/resources/data01/*           noeol
 Lib/test/test_importlib/resources/namespacedata01/*  noeol
 Lib/test/xmltestdata/*                     noeol
 
+# Shell scripts should have LF even on Windows because of Cygwin
+Lib/venv/scripts/common/activate text eol=lf
+
 # CRLF files
 [attr]dos text eol=crlf
 

Lib/test/test_venv.py

@@ -611,6 +611,21 @@ def test_zippath_from_non_installed_posix(self):
         out, err = check_output(cmd)
         self.assertTrue(zip_landmark.encode() in out)
 
+    def test_activate_shell_script_has_no_dos_newlines(self):
+        """
+        Test that the `activate` shell script contains no CR LF.
+        This is relevant for Cygwin, as the Windows build might have
+        converted line endings accidentally.
+        """
+        venv_dir = pathlib.Path(self.env_dir)
+        rmtree(venv_dir)
+        [[scripts_dir], *_] = self.ENV_SUBDIRS
+        script_path = venv_dir / scripts_dir / "activate"
+        venv.create(venv_dir)
+        with open(script_path, 'rb') as script:
+            for line in script:
+                self.assertFalse(line.endswith(b'\r\n'), line)
+
 @requireVenvCreate
 class EnsurePipTest(BaseTest):
     """Test venv module installation of pip."""

Misc/NEWS.d/next/Windows/2023-04-12-10-49-21.gh-issue-103088.Yjj-qJ.rst

@@ -0,0 +1 @@
+Fix virtual environment :file:`activate` script having incorrect line endings for Cygwin.