[GRASS-git] [OSGeo/grass] 96fbfc: Dockerfile_alpine: fix broken pip six installation...

[Markus Neteler]

  Branch: refs/heads/releasebranch_7_8
  Home:   https://github.com/OSGeo/grass
  Commit: 96fbfc59a8dc1dde7ce0ebc37a4fdaf2c3645cf8
      https://github.com/OSGeo/grass/commit/96fbfc59a8dc1dde7ce0ebc37a4fdaf2c3645cf8
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2021-05-08 (Sat, 08 May 2021)

  Changed paths:
    M docker/alpine/Dockerfile_alpine

  Log Message:
  -----------
  Dockerfile_alpine: fix broken pip six installation (#1568)

Fixes docker hub error:

```
Step 32/49 : RUN pip3 install --upgrade pip six grass-session
---> Running in 1c63e0d56789
Collecting pip
Downloading pip-21.1.1-py3-none-any.whl (1.5 MB)
Collecting six
Downloading six-1.16.0-py2.py3-none-any.whl (11 kB)
Collecting grass-session
Downloading grass_session-0.5-py2.py3-none-any.whl (31 kB)
Installing collected packages: pip, six, grass-session
Attempting uninstall: pip
Found existing installation: pip 20.0.2
Uninstalling pip-20.0.2:
Successfully uninstalled pip-20.0.2
Attempting uninstall: six
Found existing installation: six 1.15.0
ERROR: Cannot uninstall 'six'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
```