In profiling integration tests, I found a couple places where per-test
overhead could be reduced:
* Avoiding disk IO by synchronizing instead of deleting & copying test
Git repository data. This saves ~100ms per test on my machine
* When flushing queues in `PrintCurrentTest`, invoke `FlushWithContext`
in a parallel.
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
* Fix reading notes from nested trees
The GIT documentation for notes states "Permitted pathnames have the
form ab/cd/ef/.../abcdef...: a sequence of directory names of two
hexadecimal digits each followed by a filename with the rest of
the object ID."
* Add test case
* Fix new lines