splitting character in lock_expiration

[jankmet]

Splitting character '-' in lock_expiration causes problems when Thread.current.object_id is negative,
using another splitting character (';') solves this issue.

[PatrickTulskie]

Weird. To be honest I've never seen a negative object_id... Do you think you can put together a pull request with some tests? If so I can probably get it pushed out by Monday.

[jankmet]

OK, I could try, but not before Monday