Redmine

proposed change is in line 1235 of app/helpers/application_helper.rb

instead:
options.merge!({:ssl => (request && request.ssl?), :default => Setting.gravatar_default})

change to:
options.merge!({:ssl => ((Setting.protocol == 'https') || (request && request.ssl?)), :default => Setting.gravatar_default})

without that when Redmine is behind reverse proxy that do SSL gravatar links are generated as http (when everywhere else is https as expected after Setting.protocol is changed to 'https')