py/repl: Treat escaped quotes correctly in REPL continuation.

Escaped quotes are now recognised correctly in REPL when used
inside normal quotes.

Fixes: #1419

py/repl.c

@@ -59,7 +59,7 @@ bool mp_repl_continue_with_input(const char *input) {
         || str_startswith_word(input, "class")
         ;
 
-    // check for unmatched open bracket or quote
+    // check for unmatched open bracket, quote or escape quote
     #define Q_NONE (0)
     #define Q_1_SINGLE (1)
     #define Q_1_DOUBLE (2)
@@ -85,6 +85,10 @@ bool mp_repl_continue_with_input(const char *input) {
             } else if (in_quote == Q_NONE || in_quote == Q_1_DOUBLE) {
                 in_quote = Q_1_DOUBLE - in_quote;
             }
+        } else if (*i == '\\' && (i[1] == '\'' || i[1] == '"')) {
+            if (in_quote != Q_NONE) {
+                i++;
+            }
         } else if (in_quote == Q_NONE) {
             switch (*i) {
                 case '(': n_paren += 1; break;