Instead of using a custom parse function to process {}, treat it as a

set of statements and parse with yacc, then convert back to a string as
the last step. This means the rules are consistent inside and outside
{}, %if and friends work at the right time, and the final result isn't
littered with unnecessary newlines.

arguments.c

@@ -227,6 +227,11 @@ args_escape(const char *s)
 		return (escaped);
 	}
 
+	if (strchr(s, ' ') != NULL && strchr(s, '\'') == NULL) {
+		xasprintf(&escaped, "'%s'", s);
+		return (escaped);
+	}
+
 	flags = VIS_OCTAL|VIS_CSTYLE|VIS_TAB|VIS_NL;
 	if (s[strcspn(s, quoted)] != '\0')
 		flags |= VIS_DQ;