py27-serial upgrade fails with "xinstall usage: xinstall ..."

[tommy-macports@…]

My normally-fully up-to-date MacPorts installation failed a selfupgrade with

...
--->  Attempting to fetch pyserial-2.6.tar.gz from http://pypi.python.org/packages/source/p/pyserial
--->  Verifying checksum(s) for py27-serial
--->  Extracting py27-serial
--->  Configuring py27-serial
--->  Building py27-serial
--->  Staging py27-serial into destroot
Error: Target org.macports.destroot returned: xinstall usage: xinstall [-bCcpSsv] [-B suffix] [-W dir] [-f flags] [-g group] [-m mode]
               [-o owner] file1 file2
       xinstall [-bCcpSsv] [-B suffix] [-W dir] [-f flags] [-g group] [-m mode]
               [-o owner] file1 ... fileN directory
       xinstall -d [-v] [-g group] [-m mode] [-o owner] directory ...
Log for py27-serial is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_python_py-serial/py27-serial/main.log
Error: Problem while installing py27-serial
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