Filenames for CHDs change on copy

[hlarsen]

Paste the command

MAME_VERSION="0271"
DAT="../dats/mame0271.xml"
INPUT_DIR="../roms/0.271 (mame0271)-test/"
OUTPUT_DIR="../../1g1r-roms/mame-test/"

igir   -vvv   copy   zip   --dat "$DAT"   --input "$INPUT_DIR"   --output "$OUTPUT_DIR"   --input-checksum-quick   --input-checksum-archives never   --no-unlicensed   --only-retail   --single   --prefer-parent   --prefer-revision newer   --reader-threads 4   --overwrite-invalid

Describe the bug

When copying CHDs the extension is unexpectedly (unless I missed an option) removed from the filename. Not sure if this has something to do with the options I'm using.

Expected behavior

Files should be copied with no changes to the filename

Debug logs

[09:40:34.563] INFO:  CandidateWriter: 0.271 (mame0271): kinst: copying file '../roms/0.271 (mame0271)-test/kinst/kinst.chd' (89.5MB) → '../../1g1r-roms/mame-test/kinst/kinst'
[09:40:34.565] INFO:  CandidateWriter: 0.271 (mame0271): kinst2: copying file '../roms/0.271 (mame0271)-test/kinst2/kinst2.chd' (125.5MB) → '../../1g1r-roms/mame-test/kinst2/kinst2'

DAT(s) used

mame0271.xml

igir version

v3.0.1

Node.js version

v23.1.0

Operating system

Linux

Additional context

No response