Ignore errors when listing .ar archives. (Closes: Debian:#1085257)

diffoscope/comparators/ar.py

@@ -69,8 +69,8 @@ class ArFile(File):
                 ArSymbolTableDumper, self.path, other.path
             ),
             Difference.from_text_readers(
-                list_libarchive(self.path),
-                list_libarchive(other.path),
+                list_libarchive(self.path, ignore_errors=True),
+                list_libarchive(other.path, ignore_errors=True),
                 self.path,
                 other.path,
                 source="file list",

diffoscope/comparators/utils/libarchive.py

@@ -122,6 +122,14 @@ libarchive.ArchiveEntry.pathname = property(
 
 
 def list_libarchive(path, ignore_errors=False):
+    """
+    NB. Despite this method's contents being wrapped entirely in a try/except,
+    the use of yield operator means that the setting `ignore_errors` to `True`
+    will emit valid entries until there is an error, rather than a) masking all
+    entries if there is any error or b) skipping *over* errors to the next
+    entry.
+    """
+
     def force_str(val):
         # libarchive ~5 began to return uname and gname as UTF-8 whilst
         # previous versions returned bytes that required decoding.