Chapter 6.9 (glibc-2.5.1) gives an option to install just a couple of locales in order to achieve a full coverage of glibc tests.
When running grep-2.5.1a testsuite at chapter 6.37 I noticed that the results were not the same as in the test results at LFS site (http://www.linuxfromscratch.org/lfs/build-logs/6.3/Pentium4-3Ghz/chapter06-tests/093-grep), because 1 test didn't run.
This happened because the locale cs_CZ.UTF-8 need to be installed for this test run: fmbtest.sh.
This command solves the problem and I think should be metioned before the "make check" at chapter 6.37: localedef -i cs_CZ -f UTF-8 cs_CZ
I didn't built LFS-SVN, but this locale is not mentioned at glibc chapter and I compiled its grep version (2.5.3) under LFS-6.3 system and the same thing happened: without the locale the test was skipped and with the locale installed the test failed (as written in the chapter).