PEP 440 specifies how release version are understood by pip and other tools.
The last released package of docutils was in 2014.
If you install the version from Source it will not be overriden by version 0.13 when it is eventaully released.
As folks have installed 0.13 from indeterminate source versions the current version should be incremented as to allow pip to overrite a 0.13 snapshot when the next official release.
Please increment and switch the version in setup.py to be a pre-release. e.g. 0.13.1a
When a version is tagged it should be changed to a non pre release and then in the next commit incremented to the next expected version but with a pre release added
0.13.1a -> Head
0.13.1 -> when tagged for release
0.13.2a -> new head after release
Additionally snapshots can be marked with the .devXXX nominclature.
These can then all be pushed to pypi.python.org and by default pip will install the latest release unless explicitly requested via the --pre flag or a version specifier docutils>=0.13.1a
Setting up the priority, so this is not forgotten when we do our next release.
The proposal is implemented with release 0.13.1.
Thank you for reporting.