Merge 'next' branch to update packages.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Fix a bug where the src was copied in `installationPhase'.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Merge branch 'emacs-package-el' into emacs-packages-updates