This is a repeat of FL-295 & FL-310, same problem. I have solved the problem locally by temporarily adding LDFLAGS="-lpthread" to make.conf. I tried to patch the ebuild but no matter where I define LDFLAGS in the source files it fails, as though it is happening externally. Here is a more detailed summary of the failed compile:
/usr/lib/gcc/i686-pc-linux-gnu/4.6.3/../../../../i686-pc-linux-gnu/bin/ld: ../../libgit.a(run-command.o): undefined reference to symbol 'pthread_create@@GLIBC_2.1'
/usr/lib/gcc/i686-pc-linux-gnu/4.6.3/../../../../i686-pc-linux-gnu/bin/ld: note: 'pthread_create@@GLIBC_2.1' is defined in DSO /lib/libpthread.so.0 so try adding it to the linker command line
/lib/libpthread.so.0: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make: *** [svn-fe] Error 1

• ERROR: dev-vcs/git-1.8.2.1 failed (compile phase):
• emake failed
  Of course I can supply the complete log if necessary, but that's the gist of it. Also glibc updated just minutes before this occurred, it's current at 2.15-r4.
  Please note that this is on ~x86, 32bit Funtoo. From experience with the previous two bugs 64bit users seem to be immune.