BACKLOG-674 - CLONE - REG: HDP21:Hive: if we change the db-scheme, then it
won't be used until pooling connection has closed; the original will be
used instead.

What was done:
1) changed method to remove previously used "use" statement
2) added unit tests
Merge pull request #253 from kolinus/BACKLOG-674

BACKLOG-674 - CLONE - REG: HDP21:Hive: if we change the db-scheme, then ...