[PATCH] svn merge --reintegrate $other_repos

Do we want to handle 'svn merge --reintegrate $other_repos' with a hard
error (see patch below), or in some other fashion?

[[[
On the reintegrate branch:

* subversion/libsvn_client/merge.c
  (svn_client_merge_reintegrate): Handle SOURCE from a repository different
    than that of the WC.
]]]

Index: subversion/libsvn_client/merge.c
===================================================================
--- subversion/libsvn_client/merge.c (revision 28739)
+++ subversion/libsvn_client/merge.c (working copy)
@@ -5267,10 +5267,15 @@
                                                NULL, NULL, NULL,
                                                FALSE, FALSE, ctx, pool));
   SVN_ERR(svn_ra_get_repos_root(ra_session, &source_repos_root, pool));
- /* ### TODO(reint): Require that source_repos_root equals wc_repos_root,
- ### since mergeinfo doesn't come into play for cross-repository
- ### merging. */

+ /* source_repos_root and wc_repos_root are required to be the same,
+ as mergeinfo doesn't come into play for cross-repository merging. */
+ if (strcmp(source_repos_root, wc_repos_root) != 0)
+ return svn_error_createf(SVN_ERR_CLIENT_UNRELATED_RESOURCES, NULL,
+ _("'%s' must be from the same repository as "
+ "'%s'"), svn_path_local_style(source, pool),
+ svn_path_local_style(target_wcpath, pool));
+
   SVN_ERR(ensure_wc_reflects_repository_subtree(target_wcpath, ctx, pool));

   /* As the WC tree is "pure", use its last-updated-to revision as