Prevent a traceback when comparing two .rdx files directly as get_member will...

Prevent a traceback when comparing two .rdx files directly as get_member will return a file even if the file is missing and not raise a KeyError exception; we therefore explicitly test for the existence of the file.

diffoscope/comparators/rdata.py

@@ -86,17 +86,17 @@ def get_module_path_for_rdb(rdb):
     # Calculate location of parallel .rdx file
     rdx_name = "{}.rdx".format(os.path.splitext(rdb.name)[0])
 
-    try:
-        # Query the container for the full path (eg. `./path/to/foo.rdx`)...
-        rdx = rdb.container.get_member(rdx_name)
-    except KeyError:
-        try:
-            # ... falling back to looking in the same directory for when
-            # comparing two .rdb files directly
-            rdx = rdb.container.get_member(os.path.basename(rdx_name))
-        except KeyError:
-            # Corresponding .rdx does not exist
-            return
+    # Query the container for the full path (eg. `./path/to/foo.rdx`)...
+    rdx = rdb.container.get_member(rdx_name)
+
+    if not os.path.exists(rdx.path):
+        # ... falling back to looking in the same directory for when
+        # comparing two .rdb files directly
+        rdx = rdb.container.get_member(os.path.basename(rdx_name))
+
+    if not os.path.exists(rdx.path):
+        # Corresponding .rdx does not exist
+        return
 
     temp_dir = get_temporary_directory().name
     prefix = os.path.join(temp_dir, "temp")