The INFO message "a stray image seems to have been left around by a
plug-in" was annoying when GIMP is run non-interactively, and when it
was about images open from command lines. Typically this message would
be visible on our CI when the various gimp-data scripts would fail. This
could only confuse script developers.
The fact is that while a plug-in (or batch script) should definitely
clean after itself by deleting images it created (unless it gave it a
display, in which case ownership is moved to the GUI), it is absolutely
expected that images opened through the command line would still exist
at exit.
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