Fix compression-option warnings in coadds test.

Author: TallJimbo

python/lsst/pipe/tasks/mocks/simpleMapper.py

@@ -95,6 +95,28 @@ def makeButlerLocation(cls, path, dataId, mapper, suffix=None, storage=None):
         if suffix is None:
             loc = super(ExposurePersistenceType, cls).makeButlerLocation(path, dataId, mapper, suffix=None,
                                                                          storage=storage)
+            # Write options are never applicable for _sub, since that's only
+            # for read.  None of the values aside from the "NONE"s matter, but
+            # writing explicit meaningless values for all of them to appease
+            # afw is the price we pay for trying to write a non-CameraMapper
+            # Mapper. It'll all get better with Gen3 (TM).
+            options = {
+                "compression.algorithm": "NONE",
+                "compression.columns": 0,
+                "compression.rows": 0,
+                "compression.quantizeLevel": 0.0,
+                "scaling.algorithm": "NONE",
+                "scaling.bzero": 0.0,
+                "scaling.bscale": 0.0,
+                "scaling.bitpix": 0,
+                "scaling.quantizeLevel": 0.0,
+                "scaling.quantizePad": 0.0,
+                "scaling.fuzz": False,
+                "scaling.seed": 0,
+            }
+            for prefix in ("image", "mask", "variance"):
+                for k, v in options.items():
+                    loc.additionalData.set("{}.{}".format(prefix, k), v)
         elif suffix == "_sub":
             subId = dataId.copy()
             bbox = subId.pop('bbox')