Upon upgrading to Git plugin 2.0.4, I found that all my projects set up with the Git plugin had lost the URL to the repository browser (in my case, Atlassian Stash). I attempted to fix it, but the value did not save and came up blank when returning to the Configuration page. The selection of "stash" as repository type was preserved, but the "Recent Changes" page for each project was switched to Jenkins' native "detail" link instead of a link to Stash.

Reverting to 2.0.3 fixed the issue, though I had to go and manually repopulate all the repository browser URLs.