Mask edges when doBrighterFatter=True.

The edges of amplifiers that have had the brighter-fatter correction
applied may not have had the appropriate correction applied.  To
reflect this fact, ensure that the number of edge pixels matching the
kernel are masked with the EDGE bit, using the maskEdges method.

python/lsst/ip/isr/isrTask.py

@@ -1334,6 +1334,16 @@ def run(self, ccdExposure, camera=None, bias=None, linearizer=None, crosstalkSou
             bfCorr -= interpExp.getMaskedImage().getImage()
             image += bfCorr
 
+            # Applying the brighter-fatter correction applies a
+            # convolution to the science image. At the edges this
+            # convolution may not have sufficient valid pixels to
+            # produce a valid correction. Mark pixels within the size
+            # of the brighter-fatter kernel as EDGE to warn of this
+            # fact.
+            self.maskEdges(ccdExposure, numEdgePixels=numpy.max(bfKernel.shape),
+                           maskPlane="EDGE")
+            self.log.warn("Ensuring image edges are masked as SUSPECT to the brighter-fatter kernel size.")
+
             self.debugView(ccdExposure, "doBrighterFatter")
 
         if self.config.doDark: