Fix regression introduced by commit 49aec20d

Fix regression introduced by commit https://github.com/opencog/opencog/commit/49aec20db4bc2f5c9ac0b3fcd3e812e06e662581#diff-0141897e92401b447418eef495135e7eL142

```
Warning file /home/ceefour/git/opencog/opencog/nlp/scm/relex-to-logic.scm ended with unterminated input begun at line 140
scm_unprotect_object called on unprotected object
[2014-07-13 06:18:09:507] [ERROR] Caught signal 6 (Aborted) on thread 140628137334784
        Stack Trace:
        2: opencog/server/cogserver (opencog::Logger::Base::~Base() +0x7c) [0x41743e]
```

cc @sebastianruder