TestWALRestoreCorrupted is flaking

[gouthamve]

That test is flaking for some reason, needs investigation.

Ref: #162

[gouthamve]

Not sure if I am just (un) lucky but not able to replicate the flake locally. Are people seeing this locally too?

And how can I look into travis' environment?

[nipuntalukdar]

TestWALRestoreCorrupted sometime fails as the test routine and wal.cut method may be updating the same segment file in parallel resulting in error. Putting a sleep of around 2 seconds after the call to w.cut in the test routine (hopefully cut is done by 2 seconds) will fix the issue.

[gouthamve]

Fixed in #246