show warning if SSL_CERT_FILE is set and there is a certificate error

Author: dickeyxxx

lib/heroku/client.rb

@@ -507,6 +507,7 @@ def read_logs(app_name, options=[])
           http.ca_file = local_ca_file
           http.verify_callback = lambda do |preverify_ok, ssl_context|
             if (!preverify_ok) || ssl_context.error != 0
+              $stderr.puts "SSL_CERT_FILE is set. This is likely causing SSL verification to fail." if ENV['SSL_CERT_FILE']
               $stderr.puts "HTTPS_PROXY is set. This is likely causing SSL verification to fail." if ENV['HTTPS_PROXY']
               error "WARNING: Unable to verify SSL certificate for #{host}\nTo disable SSL verification, run with HEROKU_SSL_VERIFY=disable"
             end