[reports] get globals from algorithm parameter or nothing if block

doesn't redefine it. Fixes #360
4 jobs for fix_360_reports
Status Job ID Name Coverage
  Test
passed #943
lidiap2015
py27-linux

00:20:45

passed #941
beat-macosx
py27-macosx

00:11:04

failed #942
lidiap2015
py27-linux

00:03:12

failed #940
lidiap2015
py27-linux

00:03:32