Processing the failures-mr.txt file for the past month (see previous email) points to the following test units as plagging the most merge requests:
100 msxml3:domdoc (55720) 87 amstream:amstream (55725) 81 quartz:filtergraph (55758) 44 build:mac 26 d2d1:d2d1 (55765) 19 winmm:mci (55605) 15 user32:msg (55786, mostly) 13 user32:win (55766) 12 psapi:psapi_main (55744, fixed on day 3) 11 wscript.exe:run (55746, fixed on day 3) 11 tasklist.exe:tasklist (55745, fixed on day 3)
Good hunting!