It was created by Freeciv configure 3.0.6+, which was
generated by GNU Autoconf 2.71. Invocation command line was
$ ./configure --enable-gitrev --enable-debug=yes --enable-gprof --enable-client=gtk3.22,qt --with-qtver=qt5 --enable-ai-static=tex,classic
I triple checked the automatic save done when quitting the game with CTRL-Q :
when server option save in a thread is not activated, everything is ok
with save in a separate thread, the quitidle.sav is broken, only half size
alain@servical:~/.freeciv/saves$ ll -tr|tail
-rw-rw-r-- 1 alain alain 129792 mars 8 16:25 freeciv-T0447-Y01975-quitidle.sav.xz <--- normal save
-rw-rw-r-- 1 alain alain 129812 mars 8 16:34 freeciv-T0448-Y01976-auto.sav.xz
-rw-rw-r-- 1 alain alain 128516 mars 8 18:04 freeciv-T0449-Y01977-auto.sav.xz
-rw-rw-r-- 1 alain alain 129164 mars 8 18:10 freeciv-T0449-Y01977-manual.sav.xz
-rw-rw-r-- 1 alain alain 61470 mars 8 18:10 freeciv-T0449-Y01977-quitidle.sav.xz <---- threaded save
-rw-rw-r-- 1 alain alain 128900 mars 8 18:12 freeciv-T0450-Y01978-auto.sav.xz
-rw-rw-r-- 1 alain alain 129500 mars 8 18:20 freeciv-T0450-Y01978-manual.sav.xz
-rw-rw-r-- 1 alain alain 61472 mars 8 18:20 freeciv-T0450-Y01978-quitidle.sav.xz <--- threaded save
-rw-rw-r-- 1 alain alain 129408 mars 8 18:23 freeciv-T0451-Y01979-auto.sav.xz
-rw-rw-r-- 1 alain alain 129880 mars 8 18:30 freeciv-T0451-Y01979-manual.sav.xz
100% reproducible here.
The time spent for save is very small, it may be enough to just remove this option.
alain_bkr 
I triple checked the automatic save done when quitting the game with CTRL-Q :
100% reproducible here.
The time spent for save is very small, it may be enough to just remove this option.