As in other areas, Junos leverages open source software in its SLAX scripting infrastructure. This dependence on third-party software can make it difficult to determine when features were introduced and/or bugs were fixed.
To help clear things up, the Junos import history of the libcurl, libxml2, libxslt, and libslax libraries page contains the history of code imports for libcurl, libxml2, libxslt, and libslax into Junos.