Fix Github Actions (#347)

* workflows: add a workflow_dispatch trigger to start workflows manually

To be able to manually run a workflow from the Github web interface, add
a workflow_dispatch trigger.

Note that this does only work once this change has hit the default
branch.

* workflow: remove python 2.7 testing

Python 2.7 is long obsolete, deprecated and not supported any more.
Remove it from the tests. This test job is especially supposed to run on
ubuntu-20.04, which doesn't have Python 2.7 any more.

Without this patch, this workflow fails with:

  Warning: The support for python 2.7 will be removed on June 19. Related issue: actions/setup-python#672
  Version 2.7 was not found in the local cache
  Error: The version '2.7' with architecture 'x64' was not found for Ubuntu 20.04.
  The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

* setup.py: ignore flake8 warning about module import at top of file

Flake8 is unhappy with us because we violate PEP8:

rsc@leda:~/git/nodeenv$ flake8 --extend-ignore=E127 nodeenv.py tests setup.py
setup.py:16:1: E402 module level import not at top of file

Ignore this warning in this case.

* nodeenv.py: do not compare types

According to this flake8 error:

(env) rsc@leda:~/git/nodeenv$ flake8 --extend-ignore=E127 nodeenv.py tests setup.py
nodeenv.py:421:19: E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`

we should not compare types but use isinstance() instead, which can
handle subclasses as well.

See https://www.flake8rules.com/rules/E721.html for details.

.github/workflows/main.yml

@@ -5,6 +5,7 @@ on:
     branches:
     - master
   pull_request:
+  workflow_dispatch:
 
 jobs:
   tests:
@@ -15,7 +16,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-        - '2.7'
         - '3.7'
         - '3.8'
         - '3.9'

nodeenv.py

@@ -418,7 +418,7 @@ def writefile(dest, content, overwrite=True, append=False):
     Create file and write content in it
     """
     content = to_utf8(content)
-    if is_PY3 and type(content) != bytes:
+    if is_PY3 and not isinstance(content, bytes):
         content = bytes(content, 'utf-8')
     if not os.path.exists(dest):
         logger.debug(' * Writing %s ... ', dest, extra=dict(continued=True))

setup.py

@@ -13,7 +13,7 @@
 
 sys.path.insert(0, '.')
 
-from nodeenv import nodeenv_version
+from nodeenv import nodeenv_version  # noqa: E402
 
 
 def read_file(file_name):