Make /usr/bin/pip(3) work with user-installed pip 19.3+

Resolves https://bugzilla.redhat.com/show_bug.cgi?id=1767212

== Before:

$ rpm -q python3-pip
python3-pip-19.2.3-1.fc32.noarch

$ /usr/bin/pip --version
pip 19.2.3 from /usr/lib/python3.8/site-packages/pip (python 3.8)

$ pip install --user --upgrade pip
...
Successfully installed pip-19.3.1

$ /usr/bin/pip --version
Traceback (most recent call last):
  File "/usr/bin/pip", line 15, in <module>
    sys.exit(main())
TypeError: 'module' object is not callable

$ rm .local/ -rf
$ pip install --user --upgrade 'pip<10'
...
Successfully installed pip-9.0.3

$ /usr/bin/pip --version
pip 9.0.3 from /home/pythonista/.local/lib/python3.8/site-packages (python 3.8)

$ pip install --user --upgrade 'pip<9'
...
Successfully installed pip-8.1.2

$ /usr/bin/pip --version
pip 8.1.2 from /home/pythonista/.local/lib/python3.8/site-packages (python 3.8)

== After

$ rpm -q python3-pip
python3-pip-19.2.3-2.fc32.noarch

$ /usr/bin/pip --version
pip 19.2.3 from /usr/lib/python3.8/site-packages/pip (python 3.8)

$ pip install --user --upgrade pip
...
Successfully installed pip-19.3.1

$ /usr/bin/pip --version
pip 19.3.1 from /home/pythonista/.local/lib/python3.8/site-packages/pip (python 3.8)

$ pip install --user --upgrade 'pip<10'
...
Successfully installed pip-9.0.3

$ /usr/bin/pip --version
pip 9.0.3 from /home/pythonista/.local/lib/python3.8/site-packages (python 3.8)

$ pip install --user --upgrade 'pip<9'
...
Successfully installed pip-8.1.2

$ /usr/bin/pip --version
pip 8.1.2 from /home/pythonista/.local/lib/python3.8/site-packages (python 3.8)

pip-allow-different-versions.patch

@@ -1,6 +1,6 @@
 --- /usr/bin/pip3	2018-03-29 15:22:13.000000000 +0200
 +++ pip3	2018-05-04 11:49:08.098821010 +0200
-@@ -4,7 +4,12 @@
+@@ -4,7 +4,16 @@
  import re
  import sys
  
@@ -11,6 +11,10 @@
 +    # user has most probably downgraded pip in their home
 +    # so let them run it anyway until ~/.local/bin makes it in front of the PATH
 +    from pip import main
++else:
++    # user might also upgraded pip...
++    if hasattr(main, 'main'):
++        main = main.main
  
  if __name__ == '__main__':
      sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])

python-pip.spec

@@ -16,7 +16,7 @@ Name:           python-%{srcname}
 # When updating, update the bundled libraries versions bellow!
 # You can use vendor_meta.sh in the dist git repo
 Version:        19.2.3
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        A tool for installing and managing Python packages
 
 # We bundle a lot of libraries with pip, which itself is under MIT license.
@@ -95,21 +95,22 @@ Patch4:         dummy-certifi.patch
 
 # Downstream only patch
 # Users might have local installations of pip from using
-# `pip install --user --upgrade pip` on older versions.
+# `pip install --user --upgrade pip` on older/newer versions.
 # If they do that and they run `pip` or  `pip3`, the one from /usr/bin is used.
-# However that's the one from this RPM package (pip10+) and the import in there
-# fails (it tries to import from ~/.local, but older pip is there with a bit
-# different API).
+# However that's the one from this RPM package and the import in there might
+# fail (it tries to import from ~/.local, but older or newer pip is there with
+# a bit different API).
 # We add this patch as a dirty workaround to make /usr/bin/pip* work with
-# both pip10+ (from this RPM) and older pip (from whatever).
+# both pip10+ (from this RPM) and older or newer (19.3+) pip (from whatever).
 # A proper fix is to put ~/.local/bin in front of /usr/bin in the PATH,
 # however others are against that and we cannot change it for existing
 # installs/user homes anyway.
 # https://bugzilla.redhat.com/show_bug.cgi?id=1569488
 # https://bugzilla.redhat.com/show_bug.cgi?id=1571650
+# https://bugzilla.redhat.com/show_bug.cgi?id=1767212
 # WARNING: /usr/bin/pip* are entrypoints, this cannot be applied in %%prep!
 # %%patch10 doesn't work outside of %%prep, so we add it as a source
-Source10:        pip-allow-older-versions.patch
+Source10:        pip-allow-different-versions.patch
 
 %description
 pip is a package management system used to install and manage software packages
@@ -375,6 +376,9 @@ ln -sf %{buildroot}%{_bindir}/pip3 _bin/pip
 %{python_wheeldir}/%{python_wheelname}
 
 %changelog
+* Wed Oct 30 2019 Miro Hrončok <mhroncok@redhat.com> - 19.2.3-2
+- Make /usr/bin/pip(3) work with user-installed pip 19.3+ (#1767212)
+
 * Mon Sep 02 2019 Miro Hrončok <mhroncok@redhat.com> - 19.2.3-1
 - Update to 19.2.3 (#1742230)
 - Drop patch that should strip path prefixes from RECORD files, the paths are relative