A PATCH request can be issued in such a way as to be
idempotent, which also helps prevent bad outcomes [...]
Clients using this kind of patch application SHOULD use
a conditional request [...] For example, the client
can use a strong ETag [RFC2616] in an If-Match header on
the PATCH request.
So you can, but aren't obliged to.
https://help.github.com/articles/about-commit-email-addresse...