Apologies for getting back to this issue so late. This is the output of that command...
I've reproduced this against GraphicsMagick 1.3.23 built against libpng 1.6.20 (as...
gm convert for some inputs takes a long time and then corrupts the output
Images getting mangled with "-colors 256"
display and convert (probably other things too) choke on filenames with colons in
Crash opening .rscollection file