[SCM-877] AbstractSvnScmProvider#parseScmUrl() accepts file URLs with backslashes while SvnTagBranchUtils cannot handle them

**[Michael Osipov](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=michael-o)** opened **[SCM-877](https://issues.apache.org/jira/browse/SCM-877?redirect=false)** and commented

Subversion accepts URLs in the form:

```
svn co file:///D:\my\repo
```

While this URL is invalid, it is still parsed properly. Using the same URL in `` makes SvnTagBranchUtils completely fail in path calculation because it does not handle backslashes at all.

The proposed solution is that `parseUrl()` will test file URLs for backslashes and reject them since they are invalid anyway.

---

**Affects:** 1.9.5

**Issue Links:**
- [MNG-6386](https://issues.apache.org/jira/browse/MNG-6386) ${project.baseUri} is not a valid URI (according to RFC 3986)
(_**"depends upon"**_)

Start with AbstractSvnScmProvider#parseScmUrl() and trace how a file URL from reaches SvnTagBranchUtils. Reproduce the file URL containing backslashes, then verify that parsing rejects it instead of allowing path calculation to fail. Confirm behavior against the related URI constraints in the issue links.

Written by the indexing model from the issue text.