Don't error if multiple CONFIG_TESTS_FILEs resolve to the same path

Or if multiple SYSTEM_TESTS_DIRs resolve to the same path....

This happened when I introduced an entry for allactive: in a standalone
checkout of CTSM, COMP_ROOT_DIR_LND is the same as SRCROOT, so the
allactive and clm CONFIG_TESTS_FILEs and SYSTEM_TESTS_DIRs pointed to
the same path, causing an error.

Author: billsacks

CIME/XML/tests.py

@@ -22,13 +22,20 @@ def __init__(self, infile=None, files=None):
                 files = Files()
             infile = files.get_value("CONFIG_TESTS_FILE")
         GenericXML.__init__(self, infile)
-        # append any component specific config_tests.xml files
+
+        # Append any component-specific config_tests.xml files. We take care to only add a
+        # given file once, since adding a given file multiple times creates a "multiple
+        # matches" error. (This can happen if multiple CONFIG_TESTS_FILEs resolve to the
+        # same path.)
+        files_added = set()
         for comp in files.get_components("CONFIG_TESTS_FILE"):
             if comp is None:
                 continue
             infile = files.get_value("CONFIG_TESTS_FILE", attribute={"component": comp})
-            if os.path.isfile(infile):
+            infile_abspath = os.path.abspath(infile)
+            if os.path.isfile(infile) and infile_abspath not in files_added:
                 self.read(infile)
+                files_added.add(infile_abspath)
 
     def support_single_exe(self, case):
         """Checks if case supports --single-exe.

CIME/utils.py

@@ -2276,6 +2276,11 @@ def find_system_test(testname, case):
             )
             if tdir is not None:
                 tdir = os.path.abspath(tdir)
+                if tdir in fdir:
+                    # This can happen if multiple SYSTEM_TESTS_DIRs resolve to the same
+                    # path; in this case, we just want to handle the first occurrence and
+                    # skip the rest.
+                    continue
                 system_test_file = os.path.join(tdir, "{}.py".format(testname.lower()))
                 if os.path.isfile(system_test_file):
                     fdir.append(tdir)