metadata-2: SET display-name after GET

While connecting, I observe Obsidian getting some keys:

C: "METADATA * GET url website status location avatar color display-name"
S: ":fastbox BATCH +34ca6d3b27fa48f2aa688dc0d43e3232 metadata"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 766 dsc * url :key not set"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 766 dsc * website :key not set"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 766 dsc * status :key not set"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 766 dsc * location :key not set"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 761 dsc * avatar * :https://foo.tld/bar.png"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 766 dsc * color :key not set"
S: "@batch=34ca6d3b27fa48f2aa688dc0d43e3232 761 dsc * display-name * :AAAA"
S: ":fastbox BATCH -34ca6d3b27fa48f2aa688dc0d43e3232"

Obsidian has received a display-name from the server at this point, but a while later it does a SET:

C: "METADATA * SET display-name :AAAA"
S: ":fastbox 761 dsc * display-name * :AAAA"

Presumably pushing whatever display-name was in local-storage.

When there are multiple IRC clients, this will override the display-name that one may have already set in another client, at an earlier point.

No file or test is named. Search for METADATA GET/SET handling and the local-storage path, then reproduce the shown exchange with multiple clients. Done means a server-provided display-name is not later overwritten by an older local value, with coverage for this sequence.