osutil: make statfiles check for interrupts periodically
This is a simpler and faster fix for issue4878 than the contortions
performed in 502b56a9e897.
from mercurial import utildef makedate(): return 0, 0def getuser(): return 'bob'# mock the date and user apis so the output is always the samedef uisetup(ui): util.makedate = makedate util.getuser = getuser