Only append EnvPostprocessing in two situations:

In Case.read_xml(), we only want to include EnvPostprocessing object if one of
the following is true:
1. The case is being created (added Case._existing_case to make it easy to
check)
2. env_postprocessing.xml exists (which should only be the case if the file in
POSTPROCESSING_SPEC_FILE exists)

Author: mnlevy1981

CIME/XML/postprocessing.py

@@ -19,8 +19,8 @@ def __init__(self, infile=None, files=None):
             files = Files()
         if infile is None:
             infile = files.get_value("POSTPROCESSING_SPEC_FILE")
-        self._file_exists = os.path.isfile(infile)
-        if not self._file_exists:
+        self.file_exists = os.path.isfile(infile)
+        if not self.file_exists:
             return
         expect(infile, "No postprocessing file defined in {}".format(files.filename))
 

CIME/case/case.py

@@ -111,6 +111,7 @@ def __init__(self, case_root=None, read_only=True, record=False, non_local=False
                 case_root
             ),
         )
+        self._existing_case = os.path.isdir(case_root)
 
         self._caseroot = case_root
         logger.debug("Initializing Case.")
@@ -358,9 +359,10 @@ def read_xml(self):
         self._env_entryid_files.append(
             EnvWorkflow(self._caseroot, read_only=self._force_read_only)
         )
-        self._env_entryid_files.append(
-            EnvPostprocessing(self._caseroot, read_only=self._force_read_only)
-        )
+        if not self._existing_case or os.path.isfile("env_postprocessing.xml"):
+            self._env_entryid_files.append(
+                EnvPostprocessing(self._caseroot, read_only=self._force_read_only)
+            )
 
         if os.path.isfile(os.path.join(self._caseroot, "env_test.xml")):
             self._env_entryid_files.append(
@@ -1591,7 +1593,7 @@ def configure(
         workflow = Workflow(files=files)
 
         postprocessing = Postprocessing(files=files)
-        if postprocessing._file_exists:
+        if postprocessing.file_exists:
             env_postprocessing = self.get_env("postprocessing")
             env_postprocessing.add_elements_by_group(srcobj=postprocessing)