[FIX] missing-newline-extrafiles: Fix 'IOError: [Errno 22] Invalid argument' for files of size 2

[moylop260]

Fix the traceback error:

Traceback (most recent call last):
  File "./pylint_odoo/test/main.py", line 86, in test_20_expected_errors
    pylint_res = self.run_pylint(self.paths_modules)
  File "./pylint_odoo/test/main.py", line 75, in run_pylint
    return Run(self.default_options + extra_params + paths, exit=False)
  File "./pylint/lint.py", line 1332, in __init__
    linter.check(args)
  File "./pylint/lint.py", line 747, in check
    self._do_check(files_or_modules)
  File "./pylint/lint.py", line 869, in _do_check
    self.check_astroid_module(ast_node, walker, rawcheckers, tokencheckers)
  File "./pylint/lint.py", line 946, in check_astroid_module
    walker.walk(ast_node)
  File "./pylint/utils.py", line 871, in walk
    cb(astroid)
  File "./pylint_odoo/checkers/modules_odoo.py", line 108, in visit_module
    self.wrapper_visit_module(node)
  File "./pylint_odoo/misc.py", line 102, in wrapper_visit_module
    if not check_method():
  File "./pylint_odoo/checkers/modules_odoo.py", line 336, in _check_missing_newline_extrafiles
    fp.seek(-2, os.SEEK_END)
IOError: [Errno 22] Invalid argument

[coveralls]

Coverage remained the same at 100.0% when pulling c11735d on vauxoo-dev:master-fix-inval-arg-moy into fed468c on OCA:master.

[pedrobaeza]

👍

[dreispt]

👍

[luiseevaquer]

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