'main': Don't process $_.

See zsh-users#619.

Author: danielshahaf

highlighters/main/main-highlighter.zsh

@@ -434,7 +434,7 @@ _zsh_highlight_main_highlighter_highlight_list()
   # seen_alias is a map of aliases already seen to avoid loops like alias a=b b=a
   local -A seen_alias
   # Pattern for parameter names
-  readonly parameter_name_pattern='([A-Za-z_][A-Za-z0-9_]*|[0-9]+)'
+  readonly parameter_name_pattern='([A-Za-z][A-Za-z0-9_]*|_[A-Za-z0-9_]+|[0-9]+)'
   list_highlights=()
 
   # "R" for round