Signer unable to write file on long zone name

Long zone names (shown in the log as XXXX to avoid my eyes bleeding) report the following in the log, and the .axfr signed output is not written.

ods-signerd: [tools] unable to write zone XXXX: adapter failed (Unable to write file)
ods-signerd: [worker[1]] CRITICAL: failed to sign zone XXXX: Unable to write file

Case in point is a zone with the following name:

ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.test.ttt.vvv-zzzz.eeeeeeeee-mmmm

The zone contains a SOA, 4x NS and a single A. Each of the labels in the zone name is <= 63 octets, and the total length of the name is 224 octets. The longest fully-qualified name (of the A RR} is 250 octets.

I've tried tracking where this error is reported in the code which seems to surface up in adapter.c/adapter_write(). addns.c/addns_write() attempts to construct a temporary filename with .axfr.tmp tacked onto it, but this is, if I can count correctly, still below ext3's NAME_MAX (255) on Linux.

Is this a bug?