>Why some anons have to bitch about something helpful is beyond me.
I sincerely apologize. Technical background said it was impossible, but experiment showed it to be true. Someone with social media ought to notify CM to look into the site's javascript to ID the cause of this behavior and fix it.
When harvesting memes, I use a bash script to automatically convert PNGs to .jpgs with a quality setting of 93 (modest compression) before archiving (manually excluding transparent PNGs - a few of which have gotten converted to JPEG accidentally, oops).
So I just added two lines to rename any .JPEG and .jpeg files to .jpg
I don't believe it's necessary to go back and rename all the files in the memearchive but will try to ensure that all future harvests are compliant.
Our memearchive currently holds 11.74 GB. 44,637 files.
#!/bin/bash
# Convert all .png to .jpg
# 29Mar2019 Added filename conversions from .jpeg to .jpg
mogrify -format jpg -quality 93 *.png
mogrify -format jpg -quality 93 *.PNG
rm *.png
rm *.PNG
for file in *.jpeg; do mv "$file" "${file/.jpeg/.jpg}"; done
for file in *.JPEG; do mv "$file" "${file/.JPEG/.jpg}"; done