try to fix appveyor upload condition

appveyor.yml

@@ -102,17 +102,13 @@ test_script:
 after_test:
   # If tests are successful, create binary packages for the project.
   - ps: ls dist
-  # Upload whl files if building a tag on master branch. The latest Python 3
-  # is specified here because twine doesn't support older versions.
+  # Upload whl files if building a tag.
   - >
-    IF "%APPVEYOR_REPO_BRANCH%" == "master"
-    (
     IF "%APPVEYOR_REPO_TAG%" == "true"
     (
     python3 -m pip install twine &&
     python3 -m twine upload --verbose --skip-existing dist/*.whl
     )
-    )
 
 artifacts:
   # Archive the generated packages in the ci.appveyor.com build report.

tools/tasks.py

@@ -344,7 +344,7 @@ def appveyor_artifacts(ctx, vs, dest='win-dist', upload=False):
                 f.write(chunk)
     if upload:
         py = make_env(default_py, 'twine')
-        run(['twine', 'upload', '{}/*'.format(dest)])
+        run(['twine', 'upload', '--skip-existing', '{}/*'.format(dest)])
     else:
         print("You can now upload these wheels with: ")
         print("  twine upload {}/*".format(dest))