runexported.py should support run test cases with a specific tag information only.
Sent patch to the mailing list: http://lists.openembedded.org/pipermail/openembedded-core/2016-July/123478.html
Sent v2: http://lists.openembedded.org/pipermail/openembedded-core/2016-July/123486.html
moving to M2 as it missed the M1 window.
This has been implemented in commit: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=84d854c98bd201f3e92e440c1d9a64ba4f31e6da