'fmt ' and 'LIST' chunks could theoretically (but unlikely) have an odd length,
in which case the following chunk will start at the next even offset.
Added test case.
MozReview-Commit-ID: DkpBTaUqnf8
--HG--
extra : rebase_source : 0d8cfbc0d2d0da1f3317f901ef44c4fb67968dae
Gerald Squelart