Fix issue pypa#5868: TypeError in move_wheel_files().

news/5868.bugfix

@@ -0,0 +1 @@
+Fix sorting `TypeError` in `move_wheel_files()` when installing some packages.

src/pip/_internal/wheel.py

@@ -204,6 +204,13 @@ def message_about_scripts_not_on_PATH(scripts):
     return "\n".join(msg_lines)
 
 
+# We need this to avoid TypeError because values at a given tuple index
+# can be strings in some rows and integers in others.
+def sorted_outrows(outrows):
+    """Return the given "outrows" in sorted order."""
+    return sorted(outrows, key=lambda row: tuple(str(x) for x in row))
+
+
 def move_wheel_files(name, req, wheeldir, user=False, home=None, root=None,
                      pycompile=True, scheme=None, isolated=False, prefix=None,
                      warn_script_location=True):
@@ -511,7 +518,8 @@ def _get_script_text(entry):
                 outrows.append((normpath(f, lib_dir), digest, length))
             for f in installed:
                 outrows.append((installed[f], '', ''))
-            for row in sorted(outrows):
+            # Sort to simplify testing.
+            for row in sorted_outrows(outrows):
                 writer.writerow(row)
     shutil.move(temp_record, record)
 

tests/unit/test_wheel.py

@@ -33,6 +33,29 @@ def test_get_entrypoints(tmpdir, console_scripts):
     )
 
 
+@pytest.mark.parametrize("outrows, expected", [
+    ([
+        ('', '', 'a'),
+        ('', '', ''),
+    ], [
+        ('', '', ''),
+        ('', '', 'a'),
+    ]),
+    ([
+        # Include an int to check avoiding the following error:
+        # > TypeError: '<' not supported between instances of 'str' and 'int'
+        ('', '', 1),
+        ('', '', ''),
+    ], [
+        ('', '', ''),
+        ('', '', 1),
+    ]),
+])
+def test_sorted_outrows(outrows, expected):
+    actual = wheel.sorted_outrows(outrows)
+    assert actual == expected
+
+
 def test_wheel_version(tmpdir, data):
     future_wheel = 'futurewheel-1.9-py2.py3-none-any.whl'
     broken_wheel = 'brokenwheel-1.0-py2.py3-none-any.whl'