lexical.c, change semantics of an ESCAPE in a given input `string'

now simply skip it.

presumably and in accordance to what the comments seems to suggest
  ESCAPE never was really meant to be read as '['
  but was replaced just to get it out of way deeper in the for loop
  where an ESCAPE starts an ancient mechanism to reenter
    interactive input via a terminals TIOCSTI capability

src/frontend/parser/lexical.c

@@ -149,11 +149,11 @@ nloop:
 
         c = cp_readchar(&string, cp_inp_cur);
 
-        if (string && (c == ESCAPE))
-            c = '[';
-
     gotchar:
 
+        if (string && (c == ESCAPE))
+            continue;
+
         if ((c != EOF) && (c != ESCAPE))
             linebuf[j++] = (char) c;