libfaketime exceptions are not passed down the Mozilla build system properly
It seems that not all the commands passed to FAKETIME_SKIP_CMDS are passed down the Mozilla build system which leads to #13877 (moved) not being fixable. Quoting from the OS X Firefox descriptor:
# XXX Order matters as for some reason the env variable has only the first
# command assigned when it comes to the rsync parts in the build process.
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