For example, `guix build --with-source=youtube-dl=blahblah mpv` builds mpv normally, after giving a message: guix build: warning: transformation 'with-source' had no effect on mpv@0.32.0
- bug#42155: --with-source=PACKAGE=REPLACEMENT-SOURCE doesn... pkill9
- bug#42155: --with-source=PACKAGE=REPLACEMENT-SOURCE ... Efraim Flashner
- bug#42155: --with-source=PACKAGE=REPLACEMENT-SOURCE ... Jesse Gibbons