Fix an error in DiffusionBrowseTableView with SVN repsositories with no lint information
Summary: If the repository has no lint information, we don't set a 'lint' key, but try to access it unconditionally later on.
Test Plan: Looked at an SVN repository browse view, saw no errors.
Reviewers: vrana, btrahan, codeblock
Reviewed By: codeblock
CC: aran
Maniphest Tasks: T2281
Differential Revision: https://secure.phabricator.com/D4359