ports-10.12_x86_64-builder is broken

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After MacPorts 2.10.3 update the macOS Sierra builder cannot to destroot files, whether the build is successful or not: https://build.macports.org/builders/ports-10.12_x86_64-builder/builds/289149/steps/install-port/logs/stdio

DEBUG: checking for mtree violations
Error: Failed to destroot ffmpeg.
DEBUG: Error code: NONE
DEBUG: Backtrace:
    while executing
"fs_clone_capable $destroot"
    (procedure "portdestroot::destroot_finish" line 229)
    invoked from within
"$postrun $targetname"
DEBUG: dropping privileges: euid changed to 502, egid changed to 501.

Error: See /opt/local/var/macports/logs/_opt_bblocal_var_buildworker_ports_build_ports_multimedia_ffmpeg/ffmpeg/main.log for details. Error: Follow https://guide.macports.org/#project.tickets if you believe there is a bug.

Error: Processing of port ffmpeg failed

OpenPGP_0x67D486317A51FABE.asc
Description: OpenPGP public key

OpenPGP_signature.asc
Description: OpenPGP digital signature