Dylan DPC d783f399e5
Rollup merge of #84177 - ehuss:join_paths-err, r=kennytm
Fix join_paths error display.

On unix, the error from `join_paths` looked like this:

```
path segment contains separator `58`
```

This PR changes it to look like this:

```
path segment contains separator `:`
```
2021-04-15 01:27:53 +02:00
..
2020-12-07 15:22:34 +01:00
2020-11-22 17:11:41 -05:00