Support automatic upgrade using subversion

[gijskruitbosch]

Now that we have automatic upgrade (ticket 5560), it would be nice if it detected if it was on a subversion-controlled blog (should be fairly trivial to do a naive check for the .svn directory to exist) and instead of downloading, doing backups etc., simply upgraded using subversion - which should be as simple as running the svn sw command in the Codex:

​http://codex.wordpress.org/Installing/Updating_WordPress_with_Subversion

[jacobsantos]

Well, I guess it would be easy to figure out which tag you checked out and then switch you to the new one. It would also be easy to see if you are using trunk based on the version as well. What could be difficult or more work is if you are on a branch, which also has its own code.

I've often thought about doing this, but I doubt I will.

[DD32]

unless you are running under suPHP or Suexec PHP CGI or are using the PHP SSH2 module, Its impossible to run the svn up/switch commands as the same user that owns the files.

I dont like the idea of this in core, but think it'd be well suited to running as a plugin.

also, -1 to not doing the normal upgrades if a .svn folder exists, The user knows they're using SVN and chooses not to use it to upgrade it, simple as that. (It could be for a few reasons, maybe they're testing the upgrade or thats simply where they get their base installs/plugins from)

[DD32]

Due to previously mentioned issues around usernames. Better suited to a plugin.