Not entirely sure this was the cause, but it was involved. I used DISTRO_FEATURES_remove="opengl" in my local.conf and did some builds. Then I commented out that line from my local.conf, did wipe-sysroot, and tried to build mesa: $ bitbake mesa ... ERROR: Nothing PROVIDES 'mesa' ERROR: mesa was skipped: missing required distro feature ['opengl'] (not in DISTRO_FEATURES) Doing "bitbake zlib -e" confirmed that DISTRO_FEATURES did in fact have opengl in, and removing tmp/cache/ resolved the problem.
Fixed in bitbake with http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=dd36930f3f37b2e0e1258de28ac1b1fa99cf196f