Tab-completion fixes.

* Account for parsecmd() resetting the locale. The locale needs to be
  restored prior to libedit regaining control.
* Do not bother escaping unknown characters that would be taken as
  literal. It is unnecessary and interacts badly with
  --enable-parser-locale: when the parser locale is C, the global
  locale is a multibyte character set, and the text contains any
  multibyte characters when interpreted according to the global
  locale, but invalid bytes when interpreted according to the parser
  locale, escaping each invalid byte renders the resulting string
  invalid in the global locale.

src/histedit.c

@@ -250,6 +250,13 @@ complete(EditLine *el, int ch)
 			parsecmd(0);
 	}
 
+#ifdef WITH_PARSER_LOCALE
+	/* We were called with the global locale. parsecmd() may have reset to
+	 * the parser locale without getting the chance to restore. Restore it
+	 * now. */
+	uselocale(LC_GLOBAL_LOCALE);
+#endif
+
 	if (exception == EXEOF && wordtext && !(wordflags & RT_NOCOMPLETE)) {
 		char *p;
 		int flags = EXP_FULL | EXP_TILDE | EXP_COMPLETE;

src/mystring.c

@@ -304,7 +304,6 @@ shell_quote(const char *s, int style)
 				fmt = "'\\''";
 				goto fmt;
 			}
-escape:
 			*r++ = '\\';
 			goto output;
 		}
@@ -329,10 +328,8 @@ shell_quote(const char *s, int style)
 		if (c < ' ' || c > '~') {
 #endif
 #ifdef ENABLE_INTERNAL_COMPLETION
-			if (style == QS_SINGLE_QUOTED)
+			if (style > QS_DOLLAR_QUOTED)
 				goto output;
-			if (style >= QS_DOUBLE_QUOTED)
-				goto escape;
 #endif
 			fmt = "\\%03o";
 			goto fmt;