mat2: fix typo in error message when a file does not exist

Signed-off-by: Antoine Tenart <antoine.tenart@ack.tf>
9 jobs for master in 3 minutes and 6 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Linting
passed #91479
linting:bandit

00:00:17

passed #91482
linting:mypy

00:00:17

passed #91481
linting:pyflakes

00:00:16

passed #91480
linting:pylint

00:00:23

 
  Test
passed #91483
tests:archlinux

00:01:02

passed #91484
tests:debian

00:01:01

98.0%
failed #91485
tests:debian_with_bubblewrap

00:01:15

99.0%
passed #91486
tests:fedora

00:01:00

failed #91487
tests:gentoo

00:02:40

 
Name Stage Failure
failed
tests:gentoo Test
  File "/builds/jvoisin/mat2/tests/test_libmat2.py", line 130, in test_flac
self.assertEqual(meta['Cover 0'], {'Comment': 'Created with GIMP'})
AssertionError: 'harmful data' != {'Comment': 'Created with GIMP'}

----------------------------------------------------------------------
Ran 107 tests in 38.932s

FAILED (failures=7, errors=7)
ERROR: Job failed: exit code 1
failed
tests:debian_with_bubblewrap Test
libmat2/parser_factory.py      41      0     16      0   100%
libmat2/pdf.py 102 0 16 0 100%
libmat2/subprocess.py 36 0 4 0 100%
libmat2/torrent.py 93 0 28 0 100%
libmat2/video.py 37 0 8 0 100%
libmat2/web.py 111 0 46 0 100%
-----------------------------------------------------------------------
TOTAL 958 1 296 1 99%
ERROR: Job failed: exit code 1