          Return (pre_context_lineno, pre_context, context_line, post_context).
          """
          source = None
          if loader is not None and hasattr(loader, "get_source"):
              with suppress(ImportError):
                  source = loader.get_source(module_name)
              if source is not None:
                  source = source.splitlines()
          if source is None:
              with suppress(OSError, IOError):
 
</s> remove             with suppress(OSError, IOError):
 </s> add             try: </s> remove             with suppress(TemplateDoesNotExist):
 </s> add             try:
            try:
          Return (pre_context_lineno, pre_context, context_line, post_context).
          """
          source = None
          if loader is not None and hasattr(loader, "get_source"):
            try:
                  source = loader.get_source(module_name)
              if source is not None:
                  source = source.splitlines()
          if source is None:
              with suppress(OSError, IOError):
keep keep keep keep replace keep keep keep keep keep
 Reverted "Fixed #27818 -- Replaced try/except/pass with contextlib.suppress()."

This reverts commit 550cb3a365dee4edfdd1563224d5304de2a57fda
because try/except performs better. 
django/views/debug.py