Add --ignore-installed flag to generated build command

[mrvladus]

It's needed for some packages that Sdk has but Platform runtime doesn't. For example python-lxml is present in org.gnome.Sdk but not in org.gnome.Platform.

[johannesjh]

Thank you for the suggestion!

Some notes to help to proceed quickly: I think what you want to achieve is already possible in three different ways. I hope that one of the following solutions fits your need.

• You can already omit packages that you don't want to be installed (e.g., python-lxml because it is already present in the target platform) by omitting them when you invoke req2flatpak. Personally, that's how I am personally using req2flatpak.

• You can of course post-process the output of req2flatpak to suit your needs, in an automated or manual way.

• You can already customize flags such as --ignore-installed for the pip install command if using the python API instead of the commandline API, see the documentation https://johannesjh.github.io/req2flatpak/main/api.html#flatpakgenerator

...a fourth way, and probably what you've been asking for, would be to add a commandline option. Such an option would allow to specify custom flags for the pip install command. Is this what you are proposing?

How to proceed? I'd like to thank your for your proposal! And I'd be interested to hear what the other contributors think about this @real-yfprojects @cbm755 ? My thoughts are: When creating req2flatpak, we sought to keep the CLI very simple. Flexibility is given through use of its python API. For this reason, in order to keep the commandline simple, I am somewhat opposed to, but not strictly against additional CLI options.