loader: Fix repo sub-tree loading when using dump loaders
When dumping a repository sub-tree using svnrdump, svnrdump filters the repository paths outside of the sub-tree but still dumps all commits of the root repository. This means that the produced dump might contain empty commits if those modify paths outside of the sub-tree.
So ensure to have the same loading behavior as with SvnLoader class, that communicates directly with the remote repository, when loading a repository sub-tree from a remote dump. These changes ensure no empty commits will be archived and correct root directory when loading a sub-tree with SvnLoaderFromDumpArchive or SvnLoaderFromRemoteDump.
Related to #3896 (closed)
Depends on !127 (closed)
Migrated from D7163 (view on Phabricator)