A working copy is a directory that contains a collection of files which you can use as your private work area, as well as some extra files, created and maintained by Subversion. For example, each directory in your working copy contains an administrative directory named .svn.
You can have local working copies created with Subversion 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9. PyCharm handles all these formats, giving you a choice to upgrade to the new format or preserve the legacy one.
Switching to another Subversion format is always associated with a specific working copy (directory) under the Subversion control. In other words, one cannot upgrade to a newer Subversion format at the IDE level, but only to a directory under Subversion control.
tip
To check VCS association, go to File | Settings | Version Control where all mappings between the project directories (or the entire project) and VCSs are listed.
To change the format of the local working copy, do the following: