fix consistency in binary execution and existance checking

 - 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

1 files changed, 1 insertions, 1 deletions

diff --git a/scripts/build/config b/scripts/build/config
index aa275c6b9..e974bc73e 100755
--- a/scripts/build/config
+++ b/scripts/build/config
@@ -178,7 +178,7 @@ Local_arguments ()
 		case "${1}" in
 			--dump)
 				# Dump version
-				if [ -x "$(which dpkg-query 2>/dev/null)" ]
+				if [ $(which dpkg-query) ]
 				then
 					VERSION_DPKG="$(dpkg-query -f='${Version}' --show live-build)"
 				fi