Re: [PATCH v2 2/4] oidset: refactor oidset_insert_from_set()

Christian Couder [off-list ref] writes:

In a following commit, we will need to add all the oids from a set into
another set. In "list-objects-filter.c", there is already a static
function called add_all() to do that.

Let's rename this function oidset_insert_from_set() and move it into
oidset.{c,h} to make it generally available.

While at it, let's remove a useless `!= NULL`.

Makes sense.  

My initial reaction was that copying underlying bits may even be
more efficient, but that was only because silly-me did not realize
that dst can be non-empty when the operation starts.  The name of
the function is not "copy oidset" but "insert from set" that makes
it crystal clear what is going on.  Good.