hgsubversion is an extension for Mercurial that allows using Mercurial as a Subversion client.
At this point, hgsubversion is usable by users reasonably familiar with Mercurial as a VCS. It's not recommended to dive into hgsubversion as an introduction to Mercurial, since hgsubversion "bends the rules" a little and violates some of the typical assumptions of early Mercurial users.
You need to have Subversion installed with the SWIG Python bindings from Subversion 1.5 or later. You need Mercurial 1.3 or later.
If you are unfamiliar with installing Mercurial extensions, please see the UsingExtensions page in the Mercurial wiki. Look at the example for specifying an absolute path near the bottom of the page. You want to give the path to the top level of your clone of this repository.
Before using hgsubversion, I strongly encourage you to run the automated tests. Just use nose if you have it (or easy_install nose if you want it), or use python tests/run.py to run the suite with the conventional test runner. Note that because I use nose, there's a lot of stdout spew in the tests right now. The important part is that all the tests pass.
Get a new clone of an svn server:
$ hg clone <svn URI> [destination]
$ hg clone http://python-nose.googlecode.com/svn nose-hg
Note, you should pull from the root subversion directory, not specific folders (such as trunk).
Pull new revisions into an already-converted repo:
$ hg pull
For more information, see hg help svn while in a converted repo.
Support for svn:externals
All svn:externals properties are serialized into a single .hgsvnexternals file having the following syntax:
[.] common1 http://path/to/external/svn/repo1 ...additional svn:externals properties lines... [dir2] common2 -r123 http://path/to/external/svn/repo2 ...additional svn:externals properties lines...
A header line in brackets specifies the directory the property applies to, where '.' indicates the project root directory. The property content follows the header, with every content line being prefixed by a single space. Note that the property lines have a format identical to svn:externals properties as used in Subversion, and do not support the hgsubversion extended svn+http:// URL format.
Issuing the command hg svn updateexternals with the .hgsvnexternals example above would fetch the latest revision of repo1 into the subdirectory ./common1, and revision 123 of repo2 into dir2/common2. Note that .hgsvnexternals must be tracked by Mercurial before this will work. If .hgsvnexternals is created or changed, it will not be pushed to the related Subversion repository, but its contents will be used to update ``svn:externals`` properties on the related Subversion repository.