curScore.version not initiated for imported files continued from last session

Steps to reproduce bug
1. Open a MusicXML file
2. Run a plugin that displays curScore.version
(such as Plugins > Version Numbers, http://musescore.org/en/project/versionnumbers
Notice that curScore.version is undefined.
2. Edit > Preferences
3. On the General tab, choose "continue last session", and click "OK" to close dialog
4. File > Quit
5. Restart MuseScore
6. Run a plugin that displays curScore.version (such as Plugins > Version Numbers)

Expected behavior: curScore.version should be undefined in step 6 (to match the behavior of step 2)

Actual behavior: curScore.version displays a random number (see attached).

MuseScore version: 1.2 stable and r.5478 nightly

(Operating System: Windows 7)