The fetcher mirror code can go crazy creating lock filenames which exceed the
filesystem limits. When this happens, the code will loop/hang.
Handle the filename too long exception correctly but also truncate lockfile
lengths to under 256 since the worst case situation is lockfile overlap
and lack of parallelism.
(Bitbake rev: 63baf3440b16e41ac6601de21ced94a94bdf1509)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>