Fix integer->float division bug and raise on errors in testProcessCcd

ProcessCcdTask.parseAndRun was failing without raising an exception, and so the
subsequent tests would fail because the files they expected were not created,
and thus it was really unclear where the problem was. Adding --doraise to the
arguments means the failure happens in setUp, so debugging is easier.

python/lsst/obs/decam/decamCpIsr.py

@@ -1,3 +1,4 @@
+from __future__ import absolute_import, division, print_function
 #
 # LSST Data Management System
 #
@@ -42,7 +43,7 @@ def _computeEdgeSize(rawExposure, calibExposure):
     assert nx == ny, "Exposure is trimmed differently in X and Y"
     assert nx%2 == 0, "Exposure is trimmed unevenly in X"
     assert nx >= 0, "Calibration image is larger than raw data"
-    return nx/2
+    return nx//2
 
 
 class DecamCpIsrTask(DecamIsrTask):

tests/testProcessCcd.py

@@ -58,6 +58,7 @@ def setUp(self):
                      "isr.assembleCcd.setGain=False",
                      # This test uses CP-MasterCal calibration products
                      "-C", "%s/processCcdCpIsr.py" % configPath]
+        argsList.append('--doraise')
         fullResult = ProcessCcdTask.parseAndRun(args=argsList, doReturnResults=True)
         self.butler = fullResult.parsedCmd.butler
         self.config = fullResult.parsedCmd.config