The debian patch of pngcrush uses bad sh-code to parse the gas-version. Not only does it fail when /bin/sh is a symlink to dash (so that emerge will not work in this case), but I guess even with bash it will pass the wrong version (although I have not tried the latter). I attach a patch which should be applied after the current src_unpack
Created attachment 161459 [details, diff] Calculate gas version properly The patch not only fixes the version parsing but also avoids a redundant grep. Note that it must be applied after the other patches.
Thanks.. I'll will check that this is OK for next version, 1.6.7 which seems to be out. Today, hopefully.
pngcrush-1.6.7 fixes this minor issue, i don't think it qualifies as a reason to get it stable immediately.. let's just wait the default 30 days thanks for reporting