=== modified file 'common.zsh'
--- common.zsh	2017-11-30 22:33:29 +0000
+++ common.zsh	2017-11-30 21:32:35 +0000
@@ -93,49 +93,14 @@
 	done
 }
 
-is-unchanged() {
-	local -A previous
-	local arg
-
-	if ! [[ -f $FILE ]]; then
-		info "changed: missing $FILE"
-		return 1
-	fi
-	for arg in "${(s::Q)$(<$FILE)}"; do
-		if [[ "$arg" != *=* ]]; then
-			die "Malformed argument: ${(qqq)arg}"
-		fi
-		if (( $+previous[${arg%%=*}] )); then
-			die "Duplicate argument: ${arg%%=*}"
-		fi
-		previous[${arg%%=*}]=${arg#*=}
-	done
-	if [[ "${(ko)vars}" != "${(ko)previous}" ]]; then
-		info "changed: different variables"
-		info "now: ${(ko)vars}"
-		info "was: ${(ko)previous}"
-		return 2
-	fi
-	for arg in ${(k)vars}; do
-		if [[ $arg == __deps__ ]]; then
-			# TODO
-		elif [[ $vars[$arg] != $previous[$arg] ]]; then
-			info "changed: variable $arg"
-			info "now: ${(qqq)vars[$arg]}"
-			info "was: ${(qqq)previous[$arg]}"
-			return 3
-		fi
-	fi
-	return 0
-}
-
 exit-if-unchanged() {
-	if ! is-unchanged; then
+	[[ -f $FILE ]] || return
+	print-meta > $FILE.new
+	if cmp >&2 $FILE.new $FILE; then
 		cp $FILE $OUT
 		exit 0
 	else
-		print-meta > $FILE.new
-		[[ -f $FILE ]] && cp $FILE $FILE.prev
+		cp $FILE $FILE.prev
 	fi
 }