I have an SVN repository with uncommitted changes to files. There is also a change in the svn:externals property on the root folder.
How do I commit the property changes
If you only want to change the property you can do it against the repository right away, instead of against your working copy.
For example:
svn propset svn:externals "test http://yourhost.com/svn/trunk/module/test/src" --revprop -r HEAD http://yourhost.com/svn/trunk/module
See the SVN book on manipulating properties