Reflect expectation that a non-existent directory is honored and trea…

…ted like an empty directory. Closes twisted#538.

docs/cli.rst

@@ -24,8 +24,9 @@ The following options can be passed to all of the commands that explained below:
 Build the combined news file from news fragments.
 ``build`` is also assumed if no command is passed.
 
-If there are no news fragments (including an empty fragments directory), a
-notice of "no significant changes" will be added to the news file.
+If there are no news fragments (including an empty fragments directory or a
+non-existent directory), a notice of "no significant changes" will be added to
+the news file.
 
 By default, the processed news fragments are removed using ``git``, which will
 also remove the fragments directory if now empty.

src/towncrier/_builder.py

@@ -6,15 +6,12 @@
 
 import os
 import textwrap
-import traceback
 
 from collections import defaultdict
 from typing import Any, DefaultDict, Iterable, Iterator, Mapping, Sequence
 
 from jinja2 import Template
 
-from ._settings import ConfigError
-
 
 def strip_if_integer_string(s: str) -> str:
     try:
@@ -102,11 +99,8 @@ def find_fragments(
 
         try:
             files = os.listdir(section_dir)
-        except FileNotFoundError as e:
-            message = "Failed to list the news fragment files.\n{}".format(
-                "".join(traceback.format_exception_only(type(e), e)),
-            )
-            raise ConfigError(message)
+        except FileNotFoundError:
+            files = []
 
         file_content = {}