config: remove trailing comma when using breaklines

sopel/config/types.py

@@ -273,7 +273,11 @@ def parse(self, value):
             multi-line string.
         """
         if "\n" in value:
-            items = value.splitlines()
+            items = [
+                # remove trailing comma
+                # because `value,\nother` is valid in Sopel 7.x
+                item.strip(self.DELIMITER).strip()
+                for item in value.splitlines()]
         else:
             # this behavior will be:
             # - Discouraged in Sopel 7.x (in the documentation)
@@ -282,7 +286,7 @@ def parse(self, value):
             items = value.split(self.DELIMITER)
 
         value = list(filter(None, items))
-        if self.strip:
+        if self.strip:  # deprecate strip option in Sopel 8.x
             return [v.strip() for v in value]
         else:
             return value

test/test_config.py

@@ -20,8 +20,8 @@
 [spam]
 eggs = one, two, three, four, and a half
 bacons = grilled
-    burn out
-    greasy, fat, and tasty
+    burn out, 
+    , greasy, fat, and tasty
 cheese =   
     cheddar
       reblochon   
@@ -126,10 +126,10 @@ def test_listattribute_with_value_ending_in_special_chars(fakeconfig):
     assert fakeconfig.fake.listattr == ['spam', 'egg', 'sausage\\', 'bacon']
 
     fakeconfig.fake.listattr = ['spam', 'egg', 'sausage,', 'bacon']
-    assert fakeconfig.fake.listattr == ['spam', 'egg', 'sausage,', 'bacon']
+    assert fakeconfig.fake.listattr == ['spam', 'egg', 'sausage', 'bacon']
 
     fakeconfig.fake.listattr = ['spam', 'egg', 'sausage,,', 'bacon']
-    assert fakeconfig.fake.listattr == ['spam', 'egg', 'sausage,,', 'bacon']
+    assert fakeconfig.fake.listattr == ['spam', 'egg', 'sausage', 'bacon']
 
 
 def test_listattribute_with_value_containing_adjacent_special_chars(fakeconfig):