While using 1.2.0 I somehow had my fit file extension set as (reported in logs):
Default FITS extension is set to .FIT
That’s uppercase FIT. With this, scripts and manual operations resulted in files like foo_stacked.FIT.FIT.FIT.FIT (each step added a .FIT). Scripts would fail at some point not being able to match that pattern and manual processing required care.
Further I couldn’t figure out (or even if I needed to) change it to ‘.fit’. Both the UI preferences and my .siril/siril.cfg said the default was already (lower-case) .fit. Eventually I switched the UI preference to one of the other allowed extensions (.fts) and the back to .fit and now things were fine with the extension really being lowercase and scripts etc just fine.
Sorry I didn’t log this and can’t reproduce since I don’t know how I had .FIT to begin with (maybe set in an old version somehow). This was with Siril 1.2.0 on Ubuntu 20.04 loaded from ppa:lock042/siril.
Looks to me like the code that strips the extensions from files doesn’t work if the extension is set to(uppercase) .FIT and then all hell breaks loose. Reporting this in hopes the next poor soul won’t get trapped there.