reproducible: fixup usage of su

hosts/jenkins/etc/pbuilder/rebuild-hooks/B01_cleanup

@@ -7,6 +7,6 @@ set -e
 
 # cease using disorderfs
 if [ -d /tmp/disorderfs ] ; then
-	su -u pbuilder2 fusermount -u /tmp/buildd
+	su pbuilder2 -c 'fusermount -u /tmp/buildd'
 	mv /tmp/disorderfs /tmp/buildd
 fi

hosts/jenkins/etc/pbuilder/rebuild-hooks/C01_cleanup

@@ -7,6 +7,6 @@ set -e
 
 # cease using disorderfs
 if [ -d /tmp/disorderfs ] ; then
-	su -u pbuilder2 fusermount -u /tmp/buildd
+	su pbuilder2 -c 'fusermount -u /tmp/buildd'
 	mv /tmp/disorderfs /tmp/buildd
 fi

hosts/jenkins/etc/pbuilder/rebuild-hooks/D01_modify_environment

@@ -16,7 +16,7 @@ export CAPTURE_ENVIRONMENT="I capture the environment"
 if [ -x /usr/bin/disorderfs ] ; then
 	mknod -m 666 /dev/fuse c 10 229
 	mv /tmp/buildd /tmp/disorderfs
-	su -u pbuilder2 disorderfs /tmp/disorderfs /tmp/buildd
+	su pbuilder2 -c 'disorderfs /tmp/disorderfs /tmp/buildd'
 else
 	echo "Warning: disorderfs not available."
 fi