Depext: fix alpine tagged repositories handling

[rjbou]

Some examples of the new behavior

libx11-dev policy:
 1.7.1-r0:
   lib/apk/db/installed
   https://dl-cdn.alpinelinux.org/alpine/v3.13/main
 1.7.2-r0:
   @edge https://dl-cdn.alpinelinux.org/alpine/edge/main

• libx11 as installed
• libx11@edge as available

bubblewrap policy:
 0.4.1-r2:
   lib/apk/db/installed
   https://dl-cdn.alpinelinux.org/alpine/v3.13/main
   @edge https://dl-cdn.alpinelinux.org/alpine/v3.13/main
   https://dl-cdn.alpinelinux.org/alpine/edge/main
   @edge https://dl-cdn.alpinelinux.org/alpine/edge/main

• bubblewrap and bubblewrap@edge as installed

capnproto policy:
  0.8.0-r1:
    @edgecommunity https://dl-cdn.alpinelinux.org/alpine/edge/community

• capnproto-dev@edgecommunity as available

[kit-ty-kate]

bubblewrap@edge as available

I don't think this should be the behaviour in this case. For example:

bash-5.1$ apk policy gmp-dev
gmp-dev policy:
  6.2.1-r0:
    https://dl-cdn.alpinelinux.org/alpine/v3.13/main
    @edge https://dl-cdn.alpinelinux.org/alpine/v3.13/main
    https://dl-cdn.alpinelinux.org/alpine/edge/main
    @edge https://dl-cdn.alpinelinux.org/alpine/edge/main
bash-5.1$ sudo apk add gmp-dev@edge
fetch https://dl-cdn.alpinelinux.org/alpine/v3.13/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.13/community/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/edge/testing/x86_64/APKINDEX.tar.gz
(1/2) Installing libgmpxx (6.2.1-r0)
(2/2) Installing gmp-dev (6.2.1-r0)
OK: 228 MiB in 80 packages
bash-5.1$ apk policy gmp-dev
gmp-dev policy:
  6.2.1-r0:
    lib/apk/db/installed
    https://dl-cdn.alpinelinux.org/alpine/v3.13/main
    @edge https://dl-cdn.alpinelinux.org/alpine/v3.13/main
    https://dl-cdn.alpinelinux.org/alpine/edge/main
    @edge https://dl-cdn.alpinelinux.org/alpine/edge/main

Both should be marked as installed if they have the same version number

[rjbou]

Oh, I made a mistake in the example. In the code the installed state is reverted only if there is another version field, not another repo line. I'll update the main comment

[kit-ty-kate]

Some minor changes to simplify and harden the codebase, but overall it looks ok.
I haven't tested it yet, I'll do that tomorrow.

[kit-ty-kate]

Tested successfully