fix(mysql): do not generate empty completion for charset

* Instead of replacing "Index.xml" with an empty string after the
  pathname expansions, we now exclude "Index.xml" from the pathname
  pattern.

* In case that there is an empty filename as
  "/usr/share/mysql/charsets/.xml", we explicitly exclude empty
  charset names by specifying the option, -X '', for compgen.

Author: akinomyoga

completions/mysql

@@ -3,12 +3,12 @@
 _comp_xfunc_mysql_character_sets()
 {
     local -a charsets
-    _comp_expand_glob charsets '/usr/share/m{ariadb,ysql}/charsets/*.xml'
+    _comp_expand_glob charsets '/usr/share/m{ariadb,ysql}/charsets/!(Index).xml'
     charsets+=(utf8)
     charsets=("${charsets[@]##*/}")
-    charsets=("${charsets[@]%%?(Index).xml}")
+    charsets=("${charsets[@]%.xml}")
     local IFS=$'\n'
-    COMPREPLY+=($(compgen -W '${charsets[@]}' -- "$cur"))
+    COMPREPLY+=($(compgen -W '${charsets[@]}' -X '' -- "$cur"))
 }
 
 _comp_deprecate_func _mysql_character_sets _comp_xfunc_mysql_character_sets