In Subversion, show "svn checkout <uri> <directory>" in Diffusion

Summary:
Ref T10923. The old behavior was to show a full command in SVN, Mercurial, and Git, like this:

  - `git clone <uri>`
  - `hg clone <uri>`
  - `svn checkout <uri> <directory>`

In Git and Mercurial, the `<uri>` ends in something like `/nice-repository-name.git` so the default directory it creates is called `nice-repository-name/`.

In Subversion, we don't (and can't easily) do that for various reasons so we provide an explicit `<directory>` with the nice name.

In the update, I've changed things to just show the URI. I often found that I wanted the URI alone, not the whole clone command (for example, to `fetch`, `remote-add`, etc). This is also consistent with GitHub. Because we have nice URIs for Git and Mercurial, `git clone <uri>` has good behavior.

In Subversion, `svn checkout <uri>` has bad beahvior (you get a directory named `47/` or whatever). So continue showing the whole command there.

We can possibly tailor this after T4245 finishes up and we get access to `/source/nice-repository-name/` URIs.

Test Plan:
  - Viewed a Subversion repository, saw a full command.
  - Viewed a Git repository, saw only a clone URI.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10923

Differential Revision: https://secure.phabricator.com/D15888

src/applications/diffusion/controller/DiffusionRepositoryController.php

@@ -671,7 +671,16 @@ final class DiffusionRepositoryController extends DiffusionController {
 
     require_celerity_resource('diffusion-icons-css');
 
-    $display = (string)csprintf('%R', (string)$uri->getDisplayURI());
+    if ($repository->isSVN()) {
+      $display = csprintf(
+        'svn checkout %R %R',
+        (string)$uri->getDisplayURI(),
+        $repository->getCloneName());
+    } else {
+      $display = csprintf('%R', (string)$uri->getDisplayURI());
+    }
+
+    $display = (string)$display;
 
     $input = javelin_tag(
       'input',