[O] Export backends are loaded after code block evaluation

[Vicente Vera]

Org-mode version 8.3beta (release_8.3beta-584-g3953cb @
/usr/local/share/emacs/site-lisp/org/)
GNU Emacs 25.0.50.1 (i686-pc-linux-gnu, GTK+ Version 3.14.4) of 2014-11-17

Hello. Just noticed that after evaluating a code block with C-c C-c
(org-babel-execute-src-block?) all export backends stored in
'org-export-backends' are loaded---or 'required'---automatically. Once
I commented out my 'org-export-backends' setup those backends weren't
loaded, but the default ones did (ascii html icalendar latex).

Is this the intended behavior? Tried to grep my way through Org's
source files looking for a clue with no success.

Also, is there a way to prevent this from happening? It doesn't seem
extremely necessary to me.