Thumbnail random failure

Thumbnail test fails pseudo-randomly:

FAIL: test_src_input_thumbnail
==============================

[000060e000000040] main libvlc warning: cannot read /home/remi/videolan/vlc/build/src/.libs/vlc/plugins/plugins.dat: No such file or directory
test_src_input_thumbnail: ../../test/src/input/thumbnail.c:100: thumbnailer_callback: Assertion `!test_params[p_ctx->test_idx].b_expected_success && "Expected a thumbnail but got a failure"' failed.
FAIL test_src_input_thumbnail (exit status: 134)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information