in tools/run-with-tmp-session-bus.sh revision 1.6, there are two instances of
the following construct:

export FOO=bar

which for better portability should be written as

FOO=bar
export FOO

The lines in question are:

export PATH="$DBUS_TOP_BUILDDIR"/bus:$PATH
## the libtool script found by the path search should already do this, but
export LD_LIBRARY_PATH=$DBUS_TOP_BUILDDIR/dbus/.libs:$LD_LIBRARY_PATH