Automatically retry failed tests

.circleci/config.yml

@@ -23,7 +23,7 @@ jobs:
             sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 80 --slave /usr/bin/g++ g++ /usr/bin/g++-8
             sudo update-alternatives --set gcc /usr/bin/gcc-8
 
-            sudo pip install pytest-xdist pytest-instafail selenium PyYAML
+            sudo pip install pytest-xdist pytest-instafail selenium PyYAML pytest-rerunfailures
 
             # Get recent version of Firefox and geckodriver
             wget -O firefox.tar.bz2 https://download.mozilla.org/\?product\=firefox-nightly-latest-ssl\&os\=linux64\&lang\=en-US

test/test_python.py

@@ -280,6 +280,7 @@ def test_open_url(selenium):
         "pyodide.open_url('test_data.txt').read()\n") == 'HELLO\n'
 
 
+@pytest.mark.flaky(reruns=2)
 def test_run_core_python_test(python_test, selenium):
     selenium.load_package('test')
     try: