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, 2 insertions, 2 deletions

diff --git a/scripts/build/chroot_archives b/scripts/build/chroot_archives
index 472b76785..f1166ae40 100755
--- a/scripts/build/chroot_archives
+++ b/scripts/build/chroot_archives
@@ -242,7 +242,7 @@ case "${1}" in
 				cp -f cache/indices.bootstrap/*Release* chroot/var/lib/apt/lists
 			fi
 
-			if [ "${LB_APT}" = "aptitude" ] && [ ! -x /usr/bin/aptitude ]
+			if [ "${LB_APT}" = "aptitude" ] && [ ! $(which aptitude) ]
 			then
 				Chroot chroot "apt-get ${APT_OPTIONS} update"
 				Chroot chroot "apt-get ${APT_OPTIONS} install aptitude"
@@ -260,7 +260,7 @@ case "${1}" in
 			fi
 
 			# Installing aptitude
-			if [ "${LB_APT}" = "aptitude" ] && [ ! -x /chroot/usr/bin/aptitude ]
+			if [ "${LB_APT}" = "aptitude" ] && [ ! $(Chroot chroot "which aptitude") ]
 			then
 				Chroot chroot "apt-get ${APT_OPTIONS} update"
 				Chroot chroot "apt-get ${APT_OPTIONS} install aptitude"