They frequently hang for hours.
* test/lisp/filenotify-tests.el
(file-notify--test-remote-enabled-checked): Default to off on hydra.
(or file-notify--library
(file-remote-p temporary-file-directory)))
-(defvar file-notify--test-remote-enabled-checked nil
+(defvar file-notify--test-remote-enabled-checked
+ (if (getenv "EMACS_HYDRA_CI") '(t . nil))
"Cached result of `file-notify--test-remote-enabled'.
If the function did run, the value is a cons cell, the `cdr'
being the result.")