fix overwrite of `report` varname in for loops
This fixes a bug found by @joseph-betzwieser in which reuse of the report
variable in report.py results in the GPR processes trying to save results for the current report in the wrong report's path.
This fixes a bug found by @joseph-betzwieser in which reuse of the report
variable in report.py results in the GPR processes trying to save results for the current report in the wrong report's path.