POST does not work the way it did in 4.x

From my testing (test attached below) I notice these differences:

POST "foo", no content-type                                                     
  4.x : "foo" text/turtle                                                       
  5.x : 500                                                                     
POST "foo.ttl", no content-type                                                 
  4.x : "foo.ttl" text/turtle                                                   
  5.x : 500                                                                     
POST "foo", content-type=text/turtle                                            
  4.x : "foo"     text/turtle                                                   
  5.x : "foo.ttl" text/turtle                                                   
POST "foo.ttl", content-type=text/turtle                                        
  4.x : "foo.ttl.ttl" text/turtle                                               
  5.x : "foo.ttl.ttl" text/turtle                                               

Here's the test. I ran it against solid.community for 5.x and against solid.openlinksw.com:8444 for 4.x

const auth       = require('solid-auth-cli')
const text       = "<> a <#test>."

const idp  = "https://jeffz.solid.community"
const base = idp + "/public/nss5-test/"
const file = "test-file"

async function main(){
  let session = await auth.login()
  console.log("Logged in as <"+session.webId+">")
  console.log("Using folder <"+base+">\n")
  await test({
     label       : "POST, no content-type",
     extension   : "",
     contentType : ""
  })
  await test({
     label       : "POST content-type=text/turtle",
     extension   : "",
     contentType : "text/turtle"
  })
  await test({
     label       : "POST, no content-type",
     extension   : ".ttl",
     contentType : ""
  })

}
async function test(opts){
  let url = file + opts.extension
  console.log("    ",opts.label,"<"+url+">")
  let headers = {
    link : '<http://www.w3.org/ns/ldp#Resource>; rel="type"',
    slug : url,
  }
  if(opts.contentType) headers["Content-type"]=opts.contentType
  let res = await auth.fetch( base, {
    method:"POST",
    body:text,
    headers:headers
  })
  if(!res.ok){
    console.log("        ",res.status,res.statusText)
    return
  }
 let location = idp + res.headers.get("location")
 res = await auth.fetch( location )
 location = location.replace(base,'')
 if(res.ok) console.log(
      "        ",
    res.status,
    res.headers.get("content-type"),
    location
  )
  else console.log("        ",res.status,res.statusText)
}
main()

Beginne damit, den bereitgestellten Node.js-Test gegen den POST-Endpunkt des Servers auszuführen, und vergleiche die Ergebnisse für status, Location und content-type für jede Kombination aus Dateiname und Header. Erledigt ist die Aufgabe, wenn das Verhalten von 5.x korrigiert oder ausdrücklich an die in diesem Issue gezeigten Ergebnisse von 4.x angeglichen wurde.