tests: fix repeatability for test-filebranch with dirstate granularity

tests/test-filebranch

@@ -37,7 +37,7 b' echo 2b > baz'
 hg commit -m "branch b" -d "1000000 0"
 
 echo "we shouldn't have anything but n state here"
-hg debugstate --nodates
+hg debugstate --nodates | grep -v "^n"
 
 echo merging
 hg pull ../a

tests/test-filebranch.out

@@ -3,10 +3,6 b' 4 files updated, 0 files merged, 0 files'
 creating branch a
 creating branch b
 we shouldn't have anything but n state here
-n   0         -1 bar
-n   0         -1 baz
-n   0         -1 foo
-n   0         -1 quux
 merging
 pulling from ../a
 searching for changes