PEP 517: Revert to Draft status

The provisional acceptance led to some additional valid concerns being raised
with the current design in the PEP, so I'm reverting it to Draft status
while we resolve them.

pep-0517.txt

@@ -6,12 +6,11 @@ Author: Nathaniel J. Smith <njs@pobox.com>,
         Thomas Kluyver <thomas@kluyver.me.uk>
 BDFL-Delegate: Nick Coghlan <ncoghlan@gmail.com>
 Discussions-To: <distutils-sig@python.org>
-Status: Accepted
+Status: Draft
 Type: Standards Track
 Content-Type: text/x-rst
 Created: 30-Sep-2015
 Post-History: 1 Oct 2015, 25 Oct 2015
-Resolution: https://mail.python.org/pipermail/distutils-sig/2017-May/030518.html
 
 
 ==========
@@ -51,13 +50,14 @@ We therefore propose a new, relatively minimal interface for
 installation tools like ``pip`` to interact with package source trees
 and source distributions.
 
-================
- PEP Acceptance
-================
+==========================
+ Reversion to Draft Status
+==========================
 
-This PEP has been provisionally accepted for implementation in `pip` and other
-tools. It won't be considered Final until after that initial implementation
-has been released and any related feedback from end users considered.
+While this PEP was provisionally accepted for implementation in `pip` and other
+tools, some additional concerns were subsequently raised around adequately
+supporting out of tree builds. It has been reverted to Draft status while those
+concerns are being resolved.
 
 =======================
  Terminology and goals