Fix "readLinearizationData for file that is not linearized"

pikepdf 2.1.0 throws wrong type of exception in this case, so special-case it.

Closes #680
Closes #681

src/ocrmypdf/_sync.py

@@ -55,6 +55,7 @@ from ocrmypdf._validation import (
 )
 from ocrmypdf.exceptions import ExitCode, ExitCodeException
 from ocrmypdf.helpers import (
+    NeverRaise,
     available_cpu_count,
     check_pdf,
     pikepdf_enable_mmap,
@@ -301,12 +302,6 @@ def exec_concurrent(context: PdfContext):
     copy_final(pdf, options.output_file, context)
 
 
-class NeverRaise(Exception):
-    """An exception that is never raised"""
-
-    pass  # pylint: disable=unnecessary-pass
-
-
 def configure_debug_logging(log_filename, prefix: str = ''):
     """
     Create a debug log file at a specified location.

src/ocrmypdf/helpers.py

@@ -58,6 +58,10 @@ class Resolution(namedtuple('Resolution', ('x', 'y'))):
         return f"Resolution({self.x}x{self.y} dpi)"
 
 
+class NeverRaise(Exception):
+    """An exception that is never raised"""
+
+
 def safe_symlink(input_file: os.PathLike, soft_link_name: os.PathLike):
     """
     Helper function: relinks soft symbolic link if necessary
@@ -191,6 +195,12 @@ def check_pdf(input_file: Path) -> bool:
             pdf.check_linearization(sio)
         except RuntimeError:
             pass
+        except (
+            getattr(pikepdf, 'ForeignObjectError')
+            if pikepdf.__version__ == '2.1.0'  # This version may throw wrong exception
+            else NeverRaise
+        ):
+            pass
         else:
             linearize = sio.getvalue()
             if linearize: