i.e
url:http://test.musicbrainz.org/ws/2/release/?client=Clientname
body:<?xml version="1.0" encoding="UTF-8" standalone="yes"?><metadata xmlns:ns2="http://musicbrainz.org/ns/ext#-2.0" xmlns="http://musicbrainz.org/ns/mmd-2.0#"><release-list/></metadata>

Of course you shouldn't be doing this in the first place but if you do should ber handled better

Gives:
<?xml version="1.0" encoding="UTF-8"?><error><text>This edit could not be successfully created: Failed query:
'UPDATE release SET edits_pending = edits_pending + ? WHERE id IN ()'
(1)
DBD::Pg::st execute failed: ERROR: syntax error at or near ")"
LINE 1: ...lease SET edits_pending = edits_pending + '1' WHERE id IN ()
^ at /home/musicbrainz/musicbrainz-server/script/../lib/Sql.pm line 103.

at /home/musicbrainz/musicbrainz-server/script/../lib/Sql.pm line 109