yaml and Bignum

[Une bévue]

i get an error reading a yaml file :

TypeError: allocator undefined for Bignum

afaik, it's due to this line in my file :

mappings_file_mtime: !ruby/object:Bignum 1151152397

someone knows a workaround for that

this is a date in seconds since epoch, as far as i know, then i could
substract a constant, because i might change "epoch" to 2000 ...