par2cmdline: update to 0.6.11 and adopt it

[Bjørn: break overlong longDescription line]

(cherry picked from commit 001f2110bdb2300df5d600628a62a8969ff14aa5)
bup: update to 0.26 and adopt it

[Bjørn: use patchShebangs to unbreak chroot build (fixes up references
to /usr/bin/env {python,bash}]

(cherry picked from commit e5480cab83c6c291da62959a907e0d6a1c241d0e)