SSH shorthand support

[ben-edna]

In dfetch, using SSH shorthand like git@git.mycompany.com as remote and repo.git as repo-path does not work because it compounds these with / separators.
dfetch should either:

• support the shorthand syntax, or
• automatically prepend ssh:// and convert it to ssh://git@git.mycompany.com/repo.git

This would align with standard Git usage and avoid unnecessary friction.

Given the manifest 'dfetch.yaml'
    """
    manifest:
      version: '0.0'

      remotes:
        - name: internal-git
          url-base: git@git.mycompany.com

      projects:
        - name: ext/my-repo
          repo-path: my-repo.git
    """
When I run "dfetch update"
Then the project "ext/my-repo" is fetched successfully

[ben-edna]

Fixed in #1248