How to combine mv field values into string

I have a string field that I split into a variable-length multi-value, removed the last value and need to combine it back to a string value. The search below doesn't seem to work e.g.: **url /user/v1/group/status/313 /prov/provisioning/v1/group/30863** search: eval n_url= split(url, "/") |eval o_url=(mvindex(n_url,1,mvcount(n_url)-2)) |mvcombine delim="/" n_url | nomv n_url | table url, m_url, o_url