hooks/rewrite-python-shebang: simplify and check for unset $off correctly.

common/hooks/pre-pkg/03-rewrite-python-shebang.sh

@@ -2,7 +2,7 @@
 #	- rewrites python shebangs with the corresponding python version
 
 hook() {
-	local pyver= shebang= warn=
+	local pyver= shebang= warn= off=
 
 	case $pkgname in
 	python-*)
@@ -26,11 +26,10 @@ hook() {
 	shebang="#!/usr/bin/python$pyver"
 	find ${PKGDESTDIR} -type f -print0 | \
 		xargs -0 grep -H -b -m 1 "^#!.*\([[:space:]]\|/\)python\([[:space:]]\|$\)" -- | while IFS=: read -r f off _; do
-		[ "$off" -a "$off" -eq 0 ] || continue
+		[ -z "$off" ] &&  continue
 		if [ "$warn" ]; then
-			msg_warn "$pkgname: multiple python versions defined!"
-			msg_warn "$pkgname: using $pyver for shebang"
-			warn=
+			msg_warn "$pkgver: multiple python versions defined! (using $pyver for shebangs)\n"
+			unset warn
 		fi
 		echo "   Unversioned shebang replaced by '$shebang': ${f#$PKGDESTDIR}"
 		sed -i "1s@.*python@${shebang}@" -- "$f"