Add README.md describing this git branch

Signed-off-by: Benjamin Drung <[email protected]>

README.md

@@ -0,0 +1,62 @@
+reprepro with multiple versions support
+=======================================
+
+This git repository hosts a branch for reprepro which adds multiple versions
+support to it. See [Debian bug #570623](https://bugs.debian.org/570623) for
+details and updates.
+
+The upstream repository can be found on https://salsa.debian.org/brlink/reprepro
+
+Release Notes
+=============
+
+The multiple-versions patch set adds following features:
+
+* Add shunit2 based tests (Closes: [#857302](https://bugs.debian.org/857302))
+* Support multiple versions. (Closes: [#570623](https://bugs.debian.org/570623))
+* Add the commands move, movesrc, movematched, movefilter
+* Add Limit and Archive option
+
+How to keep multiple versions
+-----------------------------
+
+The default behavior of this reprepro is identical to upstream's version. To
+keep multiple versions of the same package in the archive, you have to set the
+`Limit` option to the desired maximum amount (or to 0 for unlimited). See the
+description in the man page for details.
+
+Database layout changes
+-----------------------
+
+The database layout changes from the upstream release to the
+multiple versions patch set. The difference is as following:
+
+### upstream
+
+* packages.db maps "package name" to "control file" without duplicates
+* no packagenames.db
+
+### multiple versions
+
+* packages.db maps "package name|version" to "control file" without
+duplicates
+* packagenames.db maps "package name" to "package name|version"
+allowing duplicates and duplicates sorted by dpkg --compare-versions
+descending
+
+The first time the database is opened by reprepro with multiple versions
+support, the database will be upgraded from the upstream layout to the multiple
+versions layout. *Warning*: There is no way back (but could be done with a
+simple Python script)!
+
+Howto rebase
+============
+
+1. Rebase the `multiple-versions` branch on top of the updated upstream
+`master` branch and push it to https://salsa.debian.org/bdrung/reprepro/
+
+2. Refresh the `multiple-versions-debian` branch by taking the upstream
+`debian` branch. Apply patch `debian: Switch to dh` and
+`Run shunit2 tests on build time`. Cherry-pick all commits from
+`multiple-versions`. Then apply patch `Add trace debugging output`,
+`debian: Update changelog` and `Add README.md describing this git branch`.