Fix uninstallation of user scripts

User scripts are installed to ~/.local/bin. pip was looking for scripts
to uninstall in ~/.local/lib/python3.8/site-packages/bin. This commit
makes it look in ~/.local/bin instead.

news/8733.bugfix

@@ -0,0 +1 @@
+Correctly uninstall console scripts installed to ~/.local/bin

src/pip/_internal/locations.py

@@ -75,16 +75,16 @@ def get_src_prefix():
 except AttributeError:
     user_site = site.USER_SITE
 
+bin_user = sysconfig.get_path('scripts')
+
 if WINDOWS:
     bin_py = os.path.join(sys.prefix, 'Scripts')
-    bin_user = os.path.join(user_site, 'Scripts')
     # buildout uses 'bin' on Windows too?
     if not os.path.exists(bin_py):
         bin_py = os.path.join(sys.prefix, 'bin')
         bin_user = os.path.join(user_site, 'bin')
 else:
     bin_py = os.path.join(sys.prefix, 'bin')
-    bin_user = os.path.join(user_site, 'bin')
 
     # Forcing to use /usr/local/bin for standard macOS framework installs
     # Also log to ~/Library/Logs/ for use with the Console.app log viewer

tests/functional/test_uninstall_user.py

@@ -67,6 +67,7 @@ def test_uninstall_editable_from_usersite(self, script, data):
         # uninstall
         result2 = script.pip('uninstall', '-y', 'FSPkg')
         assert not isfile(script.base_path / egg_link)
+        assert not isfile(script)
 
         assert_all_changes(
             result1,