It is possible we could crash holding a lock whilst parsing in this code.
Switch to use utils.fileslocked() in the with expression to avoid this.
This may be causing some of our strange intermittent failures in PRServ
tests.
(From OE-Core rev: 4e59db15e5df2cc3d0ae042454812a2d54cef77b)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>