checkin of percentage rank
Merge pull request #5978 from MichaelWS/master

ENH: series rank has a percentage rank option
TST: more catching of network errors
BUG: Bug in take with duplicate columns not consolidated (GH6240)
Merge pull request #6375 from jreback/take_dup

BUG: Bug in take with duplicate columns not consolidated (GH6240)