coalescing: do not try to use a self-signed certificate for coalescing verification purposes

lib/httpx/connection.rb

@@ -117,7 +117,8 @@ module HTTPX
     def coalescable?(connection)
       if @io.protocol == "h2" &&
          @origin.scheme == "https" &&
-         connection.origin.scheme == "https"
+         connection.origin.scheme == "https" &&
+         @io.can_verify_peer?
         @io.verify_hostname(connection.origin.host)
       else
         @origin == connection.origin
@@ -463,6 +464,7 @@ module HTTPX
           transition(:closing)
           transition(:closed)
           emit(:reset)
+
           @parser.reset if @parser
           transition(:idle)
           transition(:open)

lib/httpx/io/ssl.rb

@@ -27,6 +27,10 @@ module HTTPX
       super
     end
 
+    def can_verify_peer?
+      @ctx.verify_mode == OpenSSL::SSL::VERIFY_PEER
+    end
+
     def verify_hostname(host)
       return false if @ctx.verify_mode == OpenSSL::SSL::VERIFY_NONE
       return false if !@io.respond_to?(:peer_cert) || @io.peer_cert.nil?