Using 'INHERIT += "rm_work"' in local.conf is a way to save on some storage requirements, especially useful when just building an image. Documenting its existence at least in the default local.conf would be useful for people who don't have ~25 gigs to throw away for each test separately. Or mention it in some yocto documentation (ref guide?). Feel free to reassign the component/product accordingly.
I will make a note of this in the YPQS where I already note the amount of disk space needed for a build.
I added a tip to the Yocto Project Quick Start in the section that shows a sample build. The tip is as follows: TIP: To help conserve disk space during builds you can add the following statement to your local.conf file. Adding this statement deletes the work directory used for building a package once the package is built. INHERIT += "rm_work"
http://git.pokylinux.org/cgit/cgit.cgi/poky/commit/?id=f8c5a63a25f55a6c25420f131553b512eb3f3228
Fixes are in manual.