[DOC] Stop expanding GitHub style references in ChangeLog

For conciseness, omit URL expansion within ChangeLog files. Instead,
RDoc now handles external commit references when converting ChangeLog
to HTML.
C.f., ruby/rdoc#1547.

Author: nobu

tool/lib/vcs.rb

@@ -595,15 +595,6 @@ def changelog_formatter(path, arg, base_url = nil)
               s = s.join('')
             end
 
-            s.gsub!(%r[(?!<\w)([-\w]+/[-\w]+)(?:@(\h{8,40})|#(\d{5,}))\b]) do
-              path = defined?($2) ? "commit/#{$2}" : "pull/#{$3}"
-              "[#$&](https://github.com/#{$1}/#{path})"
-            end
-            if %r[^ +(https://github\.com/[^/]+/[^/]+/)commit/\h+\n(?=(?: +\n(?i: +Co-authored-by: .*\n)+)?(?:\n|\Z))] =~ s
-              issue = "#{$1}pull/"
-              s.gsub!(/\b(?:(?i:fix(?:e[sd])?) +|GH-)\K#(?=\d+\b)|\(\K#(?=\d+\))/) {issue}
-            end
-
             s.gsub!(/ +\n/, "\n")
             s.sub!(/^Notes:/, '  \&')
             w.print sep, h, s