Fixed by adding CONFIG_SHELL=/bin/bash to econf line: CONFIG_SHELL=/bin/bash ECONF_SOURCE=${S} econf "${myeconfargs[@]}" Similar report: https://discourse.libsdl.org/t/sdl-mixer-makefile-65-multiple-target-patterns-s/17502
Apparently this is no longer an issue with dash 0.5.11. I don't think it's worth fixing in the meantime, especially as most games have unstable keywords.
Resolving as OBSOLETE because all versions of dash that were affected by bug 714094 have been dropped by now.