When a release was just created, it doesn't appear yet in search results from Attach CD TOC page, and therefore one cannot attach the discid to the release he just added (i know, adding the discid then creating a new release from there would work, but the issue appears the other way).

Since the release exists, a release MBID could be used to find it, but input fields for Release (same for the Artist one) don't understand URLs and/or MBIDs (as it is the case in many places).

http://musicbrainz.org/cdtoc/attach?toc=1+16+290534+150+6755+23262+36741+79546+106670+120092+132546+145151+158012+177087+199336+209167+232603+255455+267365
is the first disc id for:
https://musicbrainz.org/release/9f082222-75fa-4653-bf89-8193a128137f