string-list: report programming error with BUG

Passing a string list that has .strdup_strings bit unset to
string_list_split(), or one that has .strdup_strings bit set to
string_list_split_in_place(), is a programmer error.  Do not use
die() to abort the execution.  Use BUG() instead.

As a developer-facing message, the message string itself should
be a lot more concise, but let's keep the original one for now.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

string-list.c

@@ -283,7 +283,7 @@ int string_list_split(struct string_list *list, const char *string,
 	const char *p = string, *end;
 
 	if (!list->strdup_strings)
-		die("internal error in string_list_split(): "
+		BUG("internal error in string_list_split(): "
 		    "list->strdup_strings must be set");
 	for (;;) {
 		count++;
@@ -309,7 +309,7 @@ int string_list_split_in_place(struct string_list *list, char *string,
 	char *p = string, *end;
 
 	if (list->strdup_strings)
-		die("internal error in string_list_split_in_place(): "
+		BUG("internal error in string_list_split_in_place(): "
 		    "list->strdup_strings must not be set");
 	for (;;) {
 		count++;