chroot: apk: fix local repos with apk.static (MR 2252)

It turns out that apk with the --root argument will still treat local
repositories relative to the host. This makes sense considering the
intended usecase, however as a result the recent change to use
apk.static for all apk commands inside the target root will break the
use of local packages.

To fix this, adjust how we populate /etc/apk/repositories, changing the
default to no longer include the local user repo. Instead we pass
--repository to apk.static with the host path to the repo.

The only time we want to add the user repo to /etc/apk/repositories
inside the chroot is when the user enters the chroot, so a special case
is added to helpers/frontend.py for the chroot command.

Signed-off-by: Caleb Connolly <caleb@postmarketos.org>

pmb/helpers/frontend.py

@@ -200,6 +200,8 @@ def chroot(args: PmbArgs):
         pmb.install.blockdevice.create_and_mount_image(args, size_boot,
                                                        size_root, size_reserve)
 
+    pmb.chroot.apk.update_repository_list(chroot, user_repository=True)
+
     # Run the command as user/root
     if user:
         logging.info(f"({chroot}) % su pmos -c '" +