Move SENSOR_EDGE pixels to the true EDGE of the PSF-Matched Warps

* Remove directWarp's original "EDGE" plane; the true edge had moved inwards
* Allow directWarp's updated EDGE pixels (from PSF-matched EDGE) into the coadd,
  but mark as SENSOR_EDGE.
* Clear mask planes that would have been rejected outside the new valid polygon,
  and reject as NO_DATA instead, so that they do not propgate to INEXACT_PSF.
  This behavior may be turned off by setting doUsePsfMatchedPolygons=False.

python/lsst/pipe/tasks/assembleCoadd.py

@@ -113,7 +113,7 @@ class AssembleCoaddConfig(CoaddBaseTask.ConfigClass):
         default=False,
     )
     doUsePsfMatchedPolygons = pexConfig.Field(
-        doc="Use ValidPolygons from shrunk PsfMatched Calexps?",
+        doc="Use ValidPolygons from shrunk Psf-Matched Calexps? Should be set to True by CompareWarp only.",
         dtype=bool,
         default=False,
     )
@@ -683,6 +683,17 @@ def applyAltMaskPlanes(self, mask, altMaskSpans):
                              and list of SpanSets to apply to the mask
         """
         for plane, spanSetList in altMaskSpans.items():
+
+            if (plane == "NO_DATA" and self.config.doUsePsfMatchedPolygons and
+                    "NO_DATA" in self.config.badMaskPlanes):
+                # Clear away any other masks outside the validPolygons. These pixels are no longer
+                # contributing to inexact PSFs, and will still be rejected because of NO_DATA.
+                # self.config.doUsePsfMatchedPolygons should be True only in CompareWarpAssemble
+                badMaskPlanes = self.getBadPixelMask()
+                print(len(spanSetList))
+                for spanSet in spanSetList:
+                    spanSet.clippedTo(mask.getBBox()).clearMask(mask, badMaskPlanes)
+
             maskClipValue = mask.addMaskPlane(plane)
             for spanSet in spanSetList:
                 spanSet.clippedTo(mask.getBBox()).setMask(mask, 2**maskClipValue)
@@ -1380,6 +1391,7 @@ def setDefaults(self):
         self.statistic = 'MEAN'
         self.doUsePsfMatchedPolygons = True
         self.badMaskPlanes.remove('EDGE')
+        self.removeMaskPlanes.append('EDGE')
         self.assembleStaticSkyModel.badMaskPlanes = ["NO_DATA", ]
         self.assembleStaticSkyModel.warpType = 'psfMatched'
         self.assembleStaticSkyModel.statistic = 'MEANCLIP'
@@ -1607,8 +1619,30 @@ def assemble(self, skyInfo, tempExpRefList, imageScalerList, weightList,
         badMaskPlanes.append("CLIPPED")
         badPixelMask = afwImage.Mask.getPlaneBitMask(badMaskPlanes)
 
-        return AssembleCoaddTask.assemble(self, skyInfo, tempExpRefList, imageScalerList, weightList,
-                                          spanSetMaskList, mask=badPixelMask)
+        retStruct = AssembleCoaddTask.assemble(self, skyInfo, tempExpRefList, imageScalerList, weightList,
+                                               spanSetMaskList, mask=badPixelMask)
+
+        # Propagate PSF-matched EDGE pixels to coadd SENSOR_EDGE and INEXACT_PSF
+        # Psf-Matching moves the real edge inwards
+        self.applyAltEdgeMask(retStruct.coaddExposure.maskedImage.mask, spanSetMaskList)
+        return retStruct
+
+    def applyAltEdgeMask(self, mask, altMaskList):
+        """!
+        \brief Propagate alt EDGE mask to SENSOR_EDGE AND INEXACT_PSF planes
+
+        @param mask: original mask
+        @param altMaskList:  List of Dictionaries containing spanSet lists.
+                             Each element contains the new mask plane name
+                             (e.g. "CLIPPED and/or "NO_DATA") as the key,
+                             and list of SpanSets to apply to the mask.
+        """
+        maskSensorEdgeBit = mask.addMaskPlane("SENSOR_EDGE")
+        maskInexactPsfBit = mask.addMaskPlane("INEXACT_PSF")
+        maskValue = 2**maskSensorEdgeBit | 2**maskInexactPsfBit
+        for visitMask in altMaskList:
+            for spanSet in visitMask['EDGE']:
+                spanSet.clippedTo(mask.getBBox()).setMask(mask, maskValue)
 
     def findArtifacts(self, templateCoadd, tempExpRefList, imageScalerList):
         """!