adjust virtualenv installation order

- Fix azure pipelines script

Signed-off-by: Dan Ryan <dan.ryan@canonical.com>

.azure-pipelines/steps/run-tests-windows.yml

@@ -43,7 +43,7 @@ steps:
     parameters:
       python_version: ${{ parameters.python_version }}
 
-  - shell: |
+  - script: |
       git submodule sync
       git submodule update --init --recursive
       pipenv run pytest -ra -n 4 --junit-xml=junit/test-results.xml tests/

.github/workflows/ci.yaml

@@ -27,7 +27,7 @@ jobs:
 
     - name: Install latest pip, setuptools, wheel
       run: |
-        python -m pip install --upgrade pip setuptools wheel virtualenv --upgrade-strategy=eager
+        python -m pip install --upgrade pip setuptools wheel --upgrade-strategy=eager
     - name: Install dependencies
       env:
         PIPENV_DEFAULT_PYTHON_VERSION: ${{ matrix.python-version }}
@@ -37,8 +37,8 @@ jobs:
       run: |
         git submodule sync
         git submodule update --init --recursive
-        python -m pip install -e . --upgrade
         python -m pip install "virtualenv<20"
+        python -m pip install -e . --upgrade
         pipenv install --deploy --dev --python=${{ steps.python-path.outputs.path }}
     - name: Run tests
       env:

pipenv/core.py

@@ -768,7 +768,7 @@ def batch_install(deps_list, procs, failed_deps_queue,
                 pypi_mirror=pypi_mirror,
                 trusted_hosts=trusted_hosts,
                 extra_indexes=extra_indexes,
-                use_pep517=True,
+                use_pep517=not failed,
             )
             c.dep = dep
             # if dep.is_vcs or dep.editable: