- prefer using `which` over hard coded paths
- it is redundant to check that the bin pointed to the return of
`which` exists and is executable, `which` already gives us
assurance of that if it returns true!
- the redirection of output (`2>/dev/null`) seems to be
unnecessary from my testing.
the instances relatnig to fdisk and losetup in functions/defaults.sh have
been left as they are since they get executed by `lb config` which can run
without sudo elevation unlike `lb build` and in that case `which` would
fail to find these binaries resulting in error.
this also fixes a bug showing an error for missing debootstrap - this tool
requires sudo privileges to run and thus is not found via a none elevated
which search.
Gbp-Dch: Short
Closes: #952927
Lyndon Brown
Daniel Baumann