[web-annotation] If-Match not used in PUT protocol test

azaroth42 has just created a new issue for 
https://github.com/w3c/web-annotation:

== If-Match not used in PUT protocol test ==

The test that checks whether an annotation can be updated using PUT 
doesn't send If-Match, and hence a server that respects the SHOULD in 
the second paragraph of 
https://www.w3.org/TR/annotation-protocol/#update-an-existing-annotation
 will fail the request, and thus fail the test.

Can we improve the test to first do a GET on the annotation URI, check
 for the ETag and then send the correct If-Match header?

Please view or discuss this issue at 
https://github.com/w3c/web-annotation/issues/386 using your GitHub 
account