duplicity 0.4.9 supports --tempdir (instead of TMPDIR ?)
duplicity 0.4.9 supports the --tempdir command line switch, which may replace the old TMPDIR environment variable usage. This should be looked at a bit.
See http://www.nongnu.org/duplicity/CHANGELOG and https://savannah.nongnu.org/patch/?6356
(from redmine: created on 2008-01-14, closed on 2010-10-12)