From https://evergreen.mongodb.com/task/wiredtiger_windows_64_compile_windows_alt_96520b5e361870911b166a54eeaac35546d2cf47_17_10_13_00_23_19 it looks like an attempt to add/remove a compiler warning has a typo:
[2017/10/13 11:30:20.143] cl : Command line warning D9014 : invalid value '133' for '/w4'; assuming '4999'