Tell reno to ignore the kilo branch

When reno 3.x runs under setuptools, it scans all of the branches it can
find, including any that look like they're closed and have an -eol tag.
The old kilo branch in this repository has a jumbled history that
somehow makes it look like it should include tags that it doesn't. We
know that there are no release notes in that branch, because reno wasn't
adopted while it was open. The releasenotes/source/index.rst links to
separate release notes in the wiki.

This patch tells reno to ignore that branch so that it doesn't throw an
exception when it gets confused about the old tag.

Change-Id: Idd56c3f37d5786daae7181c36d38d267cbf1885c
Co-Authored-By: Doug Hellmann <doug@doughellmann.com>
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

.gitignore

@@ -42,3 +42,5 @@ api-ref/build
 # Files created by releasenotes build
 releasenotes/build
 contrib/block-box/.db_data
+RELEASENOTES.rst
+releasenotes/notes/reno.cache

reno.yaml

@@ -0,0 +1,4 @@
+---
+# Ignore the kilo-eol tag because that branch does not work with reno
+# and contains no release notes.
+closed_branch_tag_re: "(.+)(?<!kilo)-eol"