Friends in testing/current image stream
This fragment together with Friends in testing/current image number makes the build link Friends in testing/current image that appears in page banners and Friends in testing and Template:Latest Releases/rc. Those also pull in a template which links to the build that uses this string, e.g. Template:candidate-jffs2-link.
Here's a semantic annotation of the same information (Edit this page to see it): official
Note that if you didn't hide this with a <noinclude> tag (or remember to use [[SMW::off]] everywhere you pull it in), then every page that transcludes this page will also be annotated with Property:Current image stream for testing.
And you have to be careful to avoid any whitespace outside the noinclude, because pages may transclude the string in the middle of a link.