Fix incorrect message buffering for images

Previously (for quite some time already), an image would not allow any subsequent input to be displayed. Probably, support for multiple images was broken since about two years. The current change should cover all known cases without breaking anything else.

Author: MrSerth

lib/runner/connection/buffer.rb

@@ -102,9 +102,9 @@ def buffering_required_for?(message)
 
     invalid_json = !valid_json?(message)
     # Second, if we have the beginning of a valid command but an invalid JSON
-    return true if invalid_json && message.start_with?(/\s*{"cmd/)
-    # Third, buffer the message if it contains long messages (e.g., an image or turtle batch commands)
-    return true if invalid_json && (message.start_with?('<img') || message.include?('"turtlebatch"'))
+    return true if invalid_json && (message.start_with?(/\s*{"cmd/) || message.include?('"turtlebatch"'))
+    # Third, buffer the message if it contains an incomplete image message tag not followed by `\r`
+    return true if invalid_json && message.start_with?('<img') && !message.end_with?(">\r")
     # Fourth, if we have an odd number of quotes and no `\r` at the end, we might have an incomplete message
     return true if (message.count('"').odd? || message.count("'").odd?) && !message.end_with?("\r")