CMake must be run twice?

The CMake build seems to have some issues with regard to
BUG_REPORT_URL (possibly other variables too).
On my Ubuntu workstation, I have to run CMake twice before it will
build the compiler with the right URL embedded.

1) Check out LLVM + Clang.
2) Run cmake.
3) Run make.
4) Force a compiler crash (e.g. PR13216).

clang-3: note: diagnostic msg: PLEASE submit a bug report to and include the crash backtrace, preprocessed source, and associated run script.

5) Note the bug report URL is empty.
6) Repeat steps 2-4.

clang-3: note: diagnostic msg: PLEASE submit a bug report to http://llvm.org/bugs/ and include the crash backtrace, preprocessed source, and associated run script.

7) Note the bug report URL is now correct.

Running CMake twice is enough to make it work, no need to build the
compiler in between. But that doesn't seem like the right fix
somehow...
--paulr