humanmade/backupwordpress — pull request #311 by pdewouters (2013-08-19 20:15:56+00:00)
Title: if exec() function is disabled, BWP can cause white screen 

Some users have reported a white screen on ALL WordPress admin pages when exec() is disabled.
Probably needs the following fixes:
check the value of pagenow() to only fire BackUpWordPress admin_init() function so we don't fail other admin screens.
fail gracefully if exec() isn't available with an error message. Or check it as a requirement on activation?