tests: fix bashism to load helpers.sh
`source` isn't available at POSIX sh.
adding empty-file
adding large-file
adding another-file
removing empty-file
removing large-file
recording removal of large-file as rename to another-file (99% similar)
% comparing two empty files caused ZeroDivisionError in the past
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding another-empty-file
removing empty-file
adding large-file
adding tiny-file
removing large-file
adding small-file
removing tiny-file
recording removal of tiny-file as rename to small-file (82% similar)
% should all fail
abort: similarity must be a number
abort: similarity must be between 0 and 100
abort: similarity must be between 0 and 100
% issue 1527
removing d/a
adding d/b
recording removal of d/a as rename to d/b (100% similar)
r 0 0 1970-01-01 00:00:00 d/a
a 0 -1 unset d/b
copy: d/a -> d/b
% no copies found here (since the target isn't in d
removing d/b
% copies here
adding c
recording removal of d/a as rename to c (100% similar)