_FORTIFY_SOURCE causes loader in Anaconda bomb out at early stage of system install when "lang=cs" is used. Other languages are probably broken too (at least Rawhide, latest Rawhide snapshot and Fedora Beta, IIRC). I'm using this parameter in my kickstart files along with PXE boot. The error message is: %n writable segment detected This seems to be a problem when translator's and output encodings are not the same (as I digged around). Without the parameter 9-Beta Anaconda installer works.
*** This bug has been marked as a duplicate of 439861 ***