release: merge back stable branch into default

Added tag v4.4.1 for changeset cbb9f1d329ae

release: Finish preparation for 4.4.1

release: updated pip2nix output for 4.4.1

release: Start preparation for 4.4.1

tags: use get_peeled to get the peeled tag sha commit instead of _peeled_refs which doesn't include them all the time.

tags: use get_peeled to get the peeled tag sha commit instead of _peeled_refs which doesn't include them all the time.

Nix: Don't depend on subversion.patches being present

Nix: Patch subversion on Darwin Things fail when running "import svn.client" due to a missing symbol.

Nix: Allow to build against current unstable For Subversion we have to start using the attribute "dev" for the include path. 16.09 supports this as well and for 16.03 a fallback with a TODO note is included.