It is not in fact a fix for #12640, only an improvement to our build
script, wrapping our calls to GIMP executables and outputting a
backtrace on a crash. This way, when people report issues during one of
the relevant calls, we may be able to diagnose.
It won't be useful for other types of failures (when the process doesn't
crash, but e.g. the script is wrong or other non-fatal bugs in GIMP).
Jehan