portability fix for test-ssh
The __del__ method of sshrepo reads the stderr of the remote process
until EOF and prints it.
If an exception is raised, this method ends up being called:
- on Linux: after the "abort: ..." message is printed
- on OS X: before the "abort: ..." message is printed
This patch explicitly flushes the stderr of the remote process before
raising a RepoError.
adding dir/bar
adding foo
dir/bar
foo
adding dir/bar_2
adding foo_2
dir/bar_2
foo_2
adding a
adding c
adding b
adding d
removing a
removing c
recording removal of a as rename to b (100% similar)