Now that Python 2 is not supported, the bytes/str boundaries are more
clear and explicit. Using six.ensure_* methods for backwards
compatibility is no longer necessary as the types are known and verified
using mypy.

One exception is tests/lib/wheel.py which allows tests to pass test
setup data as either bytes or str.

The module operations.install.wheel also remains untouched as it is
especially delicate to bytes/str mixups and the current version is
working.

Use pyupgrade to convert simple string formatting to use f-string
syntax. pyupgrade is intentionally timid and will not create an f-string
if it would make the expression longer or if the substitution parameters
are anything but simple names or dotted names.

Unnecessary since dropping Python 2 support. In Python 3, all classes
are new style classes.

Unnecessary since dropping Python 2. Python now decodes files as utf-8
by default.

Unnecessary since dropping Python 2 support.

This makes one test case from test_str_to_display a duplicate and so has
been removed.

Using typing.Text is unnecessary since dropping Python 2 support.

In Python 3, typing.Text is a simple alias of str. It exists as a
backward compatibility shim for Python 2.

Unnecessary since dropping Python 2.

Co-authored-by: NJon Dufresne <jon.dufresne@gmail.com>

Session fixtures have to use mock.patch.dict though

This is what signal.pthread_sigmask() really wants and matches signal.valid_signals() output
Co-authored-by: NChristopher Hunt <chrahunt@gmail.com>

This removes warnings from test output in python 3.8:

  /usr/lib/python3.8/signal.py:60: RuntimeWarning:
  invalid signal number 32, please use valid_signals()

Per https://groups.google.com/d/msg/pypa-dev/rUNsfIbruHM/LCEx-CB5AgAJ
the pypa-dev Google Group is now decommissioned.
Using distutils-sig instead as author/maintainer email.
Signed-off-by: NSumana Harihareswara <sh@changeset.nyc>

This reverts commit 873f1e63.

This implementation uses tests.lib.make_wheel, which allows more
flexible wheel configuration in a more structured way.

Output-wise this should be almost identical to the previous
implementation, with the following exceptions:

* Metadata-Version is bumped from 2.0 (previous implementation) to 2.1
  (from make_wheel).
* Fields previously supplied as UNKNOWN are now omitted since they are
  not significant to tests.
* The DESCRIPTION file is omitted (since the description field is now
  missing, see previous point).

This fixes https://github.com/pypa/pip/issues/7924