roundtrip: Fix handling of trailing newlines

misc/roundtrip

@@ -114,10 +114,20 @@ IFS='
 set -x
 for tags in $(find "$UNITS" -name expected.tags); do
     for name in $(sed -e 's/^\([^	]*\)	.*/\1/' "$tags"); do
-	# don't expand in the loop to handle "\n" sequence properly
-	t="$(printf '%s' "$name" | expandEscapeSequences)"
+	# Yes, there is a reason for this craziness.  We need to properly
+	# handle embedded newlines (expanded from "\n"), including trailing
+	# ones the shell would strip automatically.  To work around this, we
+	# add a dummy character at the end to inhibit stripping, and then
+	# remove it, plus the extra newline, using variable substitutions.
+	# Note: we use "printf '%s\n'" instead of "echo" because Dash's "echo"
+	# unconditionally expands some sequences, like "\t" and alike.
+	t="$(printf '%s\n' "$name" | expandEscapeSequences; printf _)"
+	t="${t%
+_}"
+
 	if [ 1 -gt $("${READTAGS}" -t "$tags" - "$t" 2>/dev/null | wc -l) ]; then
 	    printf 'FAILED: "%s" -t "%s" - "%s"\n' "${READTAGS}" "$tags" "$t"
+	    printf '	The raw tag name was "%s"\n' "$name"
 	    s=1
 	fi
     done