allow using the user's email address as a http parameter in gravatar urls for...

allow using the user's email address as a http parameter in gravatar urls for custom avatar systems. For example:
plain_url: "http://avatar.company.com/avatar/?mail=%{email}&size=%{size}"

app/helpers/application_helper.rb

@@ -66,7 +66,7 @@ module ApplicationHelper
     else
       gravatar_url = request.ssl? || gitlab_config.https ? Gitlab.config.gravatar.ssl_url : Gitlab.config.gravatar.plain_url
       user_email.strip!
-      sprintf gravatar_url, hash: Digest::MD5.hexdigest(user_email.downcase), size: size
+      sprintf gravatar_url, hash: Digest::MD5.hexdigest(user_email.downcase), size: size, email: user_email
     end
   end
 
@@ -221,4 +221,4 @@ module ApplicationHelper
   def render_markup(file_name, file_content)
     GitHub::Markup.render(file_name, file_content).html_safe
   end
-end
+end
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