[Merge] lp:~mterry/ubuntu-archive-tools/or-deps into lp:ubuntu-archive-tools

[Colin Watson]

To be honest, I'm a bit sceptical about doing this at all.  In many
cases, even if a dependency technically can be satisfied using one of
the other elements in a disjunction, we really should be updating the
outdated elements anyway; consider the recent case of dhcp3-client,
where it was entirely correct to update at least some of those elements
to say isc-dhcp-client instead.  I'm concerned that, if these stop
showing up in nbs-report, we'll stop bothering; and there's really
nowhere else we automatically notice this kind of thing.

How about, instead of removing these packages from the NBS report
altogether, we just put a note against them?  Something like "but
alternatives are present: C, D" would provide us an immediate scannable
visual clue that a disjunction is involved, without losing information
or risking false positives.

A few minor code nits:

> +            yield (dep, dep_list)
[...]
> +            for (depname, depwhy) in parse_relation_packages(stanza[field]):
[...]
> +                for (depname, depwhy) in parse_relation_packages(stanza[field]):

These days I tend to prefer to drop the unnecessary parentheses in these
cases.

> +            # Check why this rdep is here.  If it is part of an or-group, maybe
> +            # one of the other rdeps in that group are available, and this rdep
> +            # should not be blocking removal of pkg.
> +            ignore = False
> +            why = nbs[pkg][rdep][1]
> +            for whydep in why.split('|'):
> +                if whydep not in nbs:
> +                    ignore = True
> +                    break
> +            if not ignore:
> +                try:
> +                    checked_v.remove(rdep)
> +                except KeyError:
> +                    pass
> +                return False

This may be obsolete given my comments above, but FWIW, this could be
more concisely written using Python's handy for/else construction:

    why = nbs[pkg][rdep][1]
    for whydep in why.split('|'):
        if whydep not in nbs:
            break
    else:
        try:
            checked_v.remove(rdep)
        except KeyError:
            pass
        return False

-- 
https://code.launchpad.net/~mterry/ubuntu-archive-tools/or-deps/+merge/115445
Your team Ubuntu Package Archive Administrators is requested to review the proposed merge of lp:~mterry/ubuntu-archive-tools/or-deps into lp:ubuntu-archive-tools.