nielash 30517698aa bisync: make session path even shorter on tests ...

The .lck file filename length needs to be less than 255 bytes (not symbols) on
linux, and it was still too long on this test, because of the
subdir=測試_Русский_{spc}_{spc}_ě_áñ
on remotes with long names, such as TestChunkerChunk3bNoRenameLocal:

2024-04-16 14:45:54 -04:00

..

測試Русский ěáñ

…

file1.txt

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file_enconde_mañana_funcionará.txt

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filename_contains_ě_.txt

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filename_contains_ࢺ_.txt

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RCLONE_TEST

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Русский.txt

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測試_check file

…