Bug: Bad stack manipulation in 'multiline' (REPL)

'incomplete' was popping error message that should be used in case
there is no more lines to complete the input, that is, 'pushline'
returns NULL, due to end of file.

lua.c

@@ -490,10 +490,8 @@ static int incomplete (lua_State *L, int status) {
   if (status == LUA_ERRSYNTAX) {
     size_t lmsg;
     const char *msg = lua_tolstring(L, -1, &lmsg);
-    if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
-      lua_pop(L, 1);
+    if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)
       return 1;
-    }
   }
   return 0;  /* else... */
 }
@@ -508,9 +506,9 @@ static int pushline (lua_State *L, int firstline) {
   size_t l;
   const char *prmt = get_prompt(L, firstline);
   int readstatus = lua_readline(L, b, prmt);
-  if (readstatus == 0)
-    return 0;  /* no input (prompt will be popped by caller) */
   lua_pop(L, 1);  /* remove prompt */
+  if (readstatus == 0)
+    return 0;  /* no input */
   l = strlen(b);
   if (l > 0 && b[l-1] == '\n')  /* line ends with newline? */
     b[--l] = '\0';  /* remove it */
@@ -552,8 +550,9 @@ static int multiline (lua_State *L) {
     int status = luaL_loadbuffer(L, line, len, "=stdin");  /* try it */
     if (!incomplete(L, status) || !pushline(L, 0)) {
       lua_saveline(L, line);  /* keep history */
-      return status;  /* cannot or should not try to add continuation line */
+      return status;  /* should not or cannot try to add continuation line */
     }
+    lua_remove(L, -2);  /* remove error message (from incomplete line) */
     lua_pushliteral(L, "\n");  /* add newline... */
     lua_insert(L, -2);  /* ...between the two lines */
     lua_concat(L, 3);  /* join them */

testes/main.lua

@@ -349,6 +349,11 @@ prepfile("a = [[b\nc\nd\ne]]\n=a")
 RUN([[lua -e"_PROMPT='' _PROMPT2=''" -i < %s > %s]], prog, out)
 checkprogout("b\nc\nd\ne\n\n")
 
+-- input interrupted in continuation line
+prepfile("a.\n")
+RUN([[lua -i < %s > /dev/null 2> %s]], prog, out)
+checkprogout("near <eof>\n")
+
 local prompt = "alo"
 prepfile[[ --
 a = 2