src/registry.py: Update StringWithSpaceOnRight to accept the empty string as a valid value (instead of padding a space).
src/registry.py: Update StringWithSpaceOnRight to accept the empty string as a valid value (instead of padding a space).

prashantpawar/supybot-rothbot,mazaclub/mazabot-core,frumiousbandersnatch/supybot-code,haxwithaxe/supybot,ProgVal/Limnoria-test,ProgVal/Limnoria-test,kblin/supybot-gsoc,raboof/supybot,jeffmahoney/supybot,Ban3/Limnoria,Ban3/Limnoria,buildbot/supybot,mazaclub/mazabot-core