Fix trivial bugs in forced photometry from HSC-1256

A broken, pre-review version of HSC-1256 was accidentally merged to
master.

python/lsst/pipe/tasks/forcedPhotCoadd.py

@@ -85,7 +85,9 @@ def fetchReferences(self, dataRef, exposure):
         tractInfo = skyMap[dataRef.dataId["tract"]]
         patch = tuple(int(v) for v in dataRef.dataId["patch"].split(","))
         patchInfo = tractInfo.getPatchInfo(patch)
-        return self.references.fetchInPatches(dataRef, patchList=[patchInfo])
+        references = lsst.afw.table.SourceCatalog(self.references.schema)
+        references.extend(self.references.fetchInPatches(dataRef, patchList=[patchInfo]))
+        return references
 
     def attachFootprints(self, dataRef, sources, references, exposure, refWcs):
         """For coadd forced photometry, we use the deblended HeavyFootprints from the single-band
@@ -121,7 +123,7 @@ def _getConfigName(self):
         """Return the name of the config dataset
         """
         return "%s_forcedPhotCoadd_config" % (self.config.coaddName,)
-    
+
     def _getMetadataName(self):
         """Return the name of the metadata dataset
         """

python/lsst/pipe/tasks/forcedPhotImage.py

@@ -198,7 +198,7 @@ def run(self, dataRef):
         exposure = self.getExposure(dataRef)
         if exposure:
             self.log.info("Performing forced measurement on %s" % dataRef.dataId)
-            references = self.fetchReferences(dataRef, exposure))
+            references = self.fetchReferences(dataRef, exposure)
             sources = self.generateSources(dataRef, references)
             self.attachFootprints(dataRef, sources, references=references, exposure=exposure, refWcs=refWcs)
             self.measurement.run(exposure, sources, references=references, refWcs=refWcs)