The following change to the demo code fixes the problem (which is what
ConvertImageCommand() does):
$ diff demo.c.bak demo.c
68a69
> thumbnails=GetFirstImageInList(thumbnails);
Presumably some change internally stopped the GIF coder from finding the
head of the list, or the Append call changed the ordering, or something?
$ sh test.sh
libgraphicsmagick1-dev 1.4+really1.3.45+hg17696-1
Reading 1.png ... 1 frames
Reading 2.png ... 1 frames
Reading 3.png ... 1 frames
Reading 4.png ... 1 frames
Reading 5.png ... 1 frames
Reading 6.png ... 1 frames
Writing out.gif ... 6 frames
out.gif[0] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u 0m:0.000000s
out.gif[1] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u 0m:0.000034s
out.gif[2] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u 0m:0.000036s
out.gif[3] GIF 106x80+0+0 PseudoClass 128c 8-bit 9.1Ki 0.000u 0m:0.000034s
out.gif[4] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u 0m:0.000034s
out.gif[5] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u 0m:0.000035s
