Make verify-commits POSIX-compliant

contrib/verify-commits/gpg.sh

@@ -1,8 +1,9 @@
 #!/bin/sh
-INPUT=$(</dev/stdin)
+INPUT=$(cat /dev/stdin)
 VALID=false
 REVSIG=false
-IFS=$'\n'
+IFS='
+'
 for LINE in $(echo "$INPUT" | gpg --trust-model always "$@" 2>/dev/null); do
 	case "$LINE" in
 	"[GNUPG:] VALIDSIG "*)
@@ -13,10 +14,9 @@ for LINE in $(echo "$INPUT" | gpg --trust-model always "$@" 2>/dev/null); do
 	"[GNUPG:] REVKEYSIG "*)
 		[ "$BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG" != 1 ] && exit 1
 		while read KEY; do
-			case "$LINE" in "[GNUPG:] REVKEYSIG ${KEY:24:40} "*)
+			case "$LINE" in "[GNUPG:] REVKEYSIG ${KEY#????????????????????????} "*)
 				REVSIG=true
-				GOODREVSIG="[GNUPG:] GOODSIG ${KEY:24:40} "
-				;;
+				GOODREVSIG="[GNUPG:] GOODSIG ${KEY#????????????????????????} "
 			esac
 		done < ./contrib/verify-commits/trusted-keys
 		;;