The buildfarm animal fairywren has been failing the tests for pg_basebackup because it can't create a file with a path longer than 255 chars. This has just been tripped because for release 16 it's running TAP tests, and the branch name is part of the file path, and "REL_16_STABLE" is longer than "HEAD". I did think of chdir'ing into the directory to create the file, but experimentation shows that doesn't solve matters. I also adjusted the machine's settings related to long file names, but to no avail, so for now I propose to reduce slightly the name of the long file so it still exercises the check for file names longer than 100 but doesn't trip this up on fairywren. But that's a bandaid. I don't have a good solution for now.
cheers
andrew
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Andrew Dunstan
EDB: https://www.enterprisedb.com