Fix for env_batch.zip

CIME/XML/env_batch.py

@@ -1421,10 +1421,24 @@ def zip(self, other, name):
                 other_pnode = None
 
             for node1 in self.get_children(root=self_pnode):
-                for node2 in other.scan_children(
+                other_children = other.scan_children(
                     node1.name, attributes=node1.attrib, root=other_pnode
-                ):
-                    yield node1, node2
+                )
+                real_other_children = []
+                if not node1.attrib:
+                    # Only keep elements that had no attributes. If node1 has no attributes
+                    # scan_children will return ALL elements with matching name.
+                    for other_child in other_children:
+                        if node1.attrib == other_child.attrib:
+                            real_other_children.append(other_child)
+                else:
+                    real_other_children = other_children
+
+                expect(
+                    len(real_other_children) == 1,
+                    "Multiple matches in zip for single node",
+                )
+                yield node1, real_other_children[0]
 
     def _compare_arg(self, index, arg1, arg2):
         try:

CIME/tests/test_unit_xml_env_batch.py

@@ -127,6 +127,59 @@
 </file>"""
 
 
+XML_CHECK = b"""<?xml version="1.0"?>
+<file id="env_batch.xml" version="2.0">
+  <header>
+      These variables may be changed anytime during a run, they
+      control arguments to the batch submit command.
+    </header>
+  <group id="config_batch">
+    <entry id="BATCH_SYSTEM" value="nersc_slurm">
+      <type>char</type>
+      <valid_values>miller_slurm,nersc_slurm,lc_slurm,moab,pbs,pbspro,lsf,slurm,cobalt,cobalt_theta,slurm_single_node,none</valid_values>
+      <desc>The batch system type to use for this machine.</desc>
+    </entry>
+  </group>
+  <group id="job_submission">
+    <entry id="PROJECT_REQUIRED" value="TRUE">
+      <type>logical</type>
+      <valid_values>TRUE,FALSE</valid_values>
+      <desc>whether the PROJECT value is required on this machine</desc>
+    </entry>
+  </group>
+  <batch_system MACH="pm-gpu" type="nersc_slurm">
+    <directives>
+      <directive> --constraint=gpu</directive>
+    </directives>
+    <directives COMPSET="!.*MMF.*" compiler="gnugpu">
+      <directive> --gpus-per-node=4</directive>
+      <directive> --gpu-bind=none</directive>
+    </directives>
+    <directives COMPSET=".*MMF.*" compiler="gnugpu">
+      <directive> --gpus-per-task=1</directive>
+      <directive> --gpu-bind=map_gpu:0,1,2,3</directive>
+    </directives>
+    <directives compiler="nvidiagpu">
+      <directive> --gpus-per-node=4</directive>
+      <directive> --gpu-bind=none</directive>
+    </directives>
+    <directives compiler="gnu">
+      <directive> -G 0</directive>
+    </directives>
+    <directives compiler="nvidia">
+      <directive> -G 0</directive>
+    </directives>
+    <queues>
+      <queue default="true" nodemax="1792" walltimemax="00:45:00">regular</queue>
+      <queue nodemax="1792" strict="true" walltimemax="00:45:00">preempt</queue>
+      <queue nodemax="1792" strict="true" walltimemax="00:45:00">shared</queue>
+      <queue nodemax="1792" strict="true" walltimemax="00:45:00">overrun</queue>
+      <queue nodemax="4" strict="true" walltimemax="00:15:00">debug</queue>
+    </queues>
+  </batch_system>
+</file>"""
+
+
 def _open_temp_file(stack, data):
     tfile = stack.enter_context(tempfile.NamedTemporaryFile())
 
@@ -175,6 +228,21 @@ def test_compare_xml(self):
 
         assert diff2 == expected_diff2
 
+    def test_compare_xml_same(self):
+        with ExitStack() as stack:
+            file1 = _open_temp_file(stack, XML_CHECK)
+            batch1 = EnvBatch(infile=file1.name)
+
+            file2 = _open_temp_file(stack, XML_CHECK)
+            batch2 = EnvBatch(infile=file2.name)
+
+            diff = batch1.compare_xml(batch2)
+            diff2 = batch2.compare_xml(batch1)
+
+        expected_diff = {}
+        assert diff == expected_diff, f"{diff}"
+        assert diff2 == expected_diff, f"{diff2}"
+
     @mock.patch("CIME.XML.env_batch.EnvBatch._submit_single_job")
     def test_submit_jobs(self, _submit_single_job):
         case = mock.MagicMock()