Extend support for preserving the current environment to the
for-all-repos plugin with the --preserve-env flag.
This eases the usage of dynamic configuration done via environment
variables within the for-all-repos plugin, e.g. when calling a script.
Signed-off-by: Jasper Orschulko <jasper@fancydomain.eu>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>