Fixed checks for enabled files in existing plugins

plugins/available/z.plugin.bash

@@ -15,7 +15,7 @@ about-plugin '                              z is DEPRECATED, use fasd instead'
 #   * z -t foo  # goes to most recently accessed dir matching foo
 #   * z -l foo  # list all dirs matching foo (by frecency)
 
-if [ -e $BASH_IT/plugins/enabled/fasd.plugin.bash ]; then
+if [ -e "${BASH_IT}/plugins/enabled/fasd.plugin.bash" ] || [ -e "${BASH_IT}/plugins/enabled/*${BASH_IT_LOAD_PRIORITY_SEPARATOR}fasd.plugin.bash" ]; then
     printf '%s\n' 'sorry, the z plugin is incompatible with the fasd plugin. you may use either, but not both.'
     return
 fi