Use a different marker so we don't clash with other jib json outputs

[loosebazooka]

This is to potentially protect us from the case where we run sync and files tasks together.

[TadCordle]

I wonder if we should use a more specific BEGIN JIB JSON message for the init and files tasks too (like BEGIN JIB INIT JSON and BEGIN JIB FILES JSON) Nevermind, I guess that'd break backwards compatibility.

[loosebazooka]

Nevermind, I guess that'd break backwards compatibility.

Oh I didn't realize init had one too :. But, yeah it's probably worth coming up with a strategy for this eventually.

[briandealwis]

Could we make this header a bit more easy to identify with a common prefix, and future-proofed by embedding a version?

BEGIN JIB JSON: SYNCMAP v1

So we can scan looking for BEGIN JIB JSON and if we're missing a colon then it indicates an older Jib.

We can now force a minimum Jib version, but that's quite disruptive. It might be worth looking at HTTP and how it handles version negotiation.

[loosebazooka]

Updating this with new style, PTAL

Changed format