[bugfix] Properly opt out of zinc's fingerprinting of Resources.

Review Request #3185 - Created Nov. 27, 2015 and submitted

Patrick Lawson
jsirois, mateor, stuhood, zundel

Properly opt out of zinc's fingerprinting of Resources.

Internally at Foursquare we have a task that injects a Resource
target dependency on every JvmLibrary in the graph (a temporary
hack), and we noticed that this task getting scheduled before
compilation vs after compilation results in totally different
fingerprints for the entire graph (wrt zinc's FP strategy).
This is because the FP strategy isn't using the mechanism to opt
out of fingerprinting a target (return None)--therefore even
though the resource target's contents aren't rolled into the fingerprint,
the resource target's presence in the graph affects the transitive
fingerprints of dependees.

It's plausible that we want to go further here and opt out of
fingerprinting anything except JvmTarget and JarLibrary subclasses
here, since in theory all other dependencies are extraneous and irrelevant
from zinc's perspective.

CI is green: https://travis-ci.org/pantsbuild/pants/builds/114591351

Benjy Weinberger
Patrick Lawson
Eric Ayers
Stu Hood
Eric Ayers
Patrick Lawson
Patrick Lawson
Patrick Lawson
Review request changed

Status: Closed (submitted)

Change Summary:

Upstream at d1fd14ac90d1c30a737448cc48fdd786b5108b5c