backup: revert to catching fewer exceptions

We specifically don't want to catch BrokenPipeError; just list
file-related ones that we might expect to see if we hit bad
permissions, disk errors, or race conditions.

README.md

@@ -123,6 +123,8 @@ Notes
     pip install -e .[llfuse]
     pyinstaller --clean --noconfirm scripts/borg.exe.spec
 
+Then see `dist/borg.exe`.  Confirm the version with `dist/borg.exe --version`.
+
 *Note:* This uses the deprecated `llfuse` instead of the newer `pyfuse3`.
 `pyfuse3` doesn't work because, at minimum, it pulls in `trio` which
 requires `ssl` which is explicitly excluded by

backup.py

@@ -219,7 +219,10 @@ class Backup:
                     for entry in it:
                         self.scan(path=entry.path, parent_st=st)
 
-        except OSError as e:
+        except (FileNotFoundError,
+                IsADirectoryError,
+                NotADirectoryError,
+                PermissionError) as e:
             self.log('E', f"can't read {pstr(path)}: {str(e)}")
             return