This bug depends on cmake version.

For cmake 2.6 (which is still in use for some pushbuild trees)
the main build would succeed, even if create_initial_db failed.

The problem was the chaining of commands in the CUSTOM_COMMAND
to produce 'initdb.dep'. It first invokes cmake to run mysqld,
then invokes 'touch' to create the file. Moving the 'touch'
command makes the error propagate properly for both cmake 2.6 and 2.8