remotefilelog: tweak corrupt cache test to grep more flexibly
I'm about to fix the abuse of RuntimeError here, which breaks the test
if I don't do this.
Differential Revision: https://phab.mercurial-scm.org/D11005
pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2
pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2