revert: next test already tests wiped keys; add comment

Author: MichaelChirico

inst/tests/mergelist.Rraw

@@ -39,8 +39,9 @@ test(12.06, cbindlist(list(data.table(), data.table(a=1:2), data.table(b=1:2))),
 test(12.07, cbindlist(list(data.table(), data.table(a=1:2), list(b=1:2))), data.table(a=1:2, b=1:2))
 test(12.08, cbindlist(list(data.table(a=integer()), list(b=integer()))), data.table(a=integer(), b=integer()))
 ## duplicated names
-test(12.09, cbindlist(list(data.table(a=1L, b=2L, key="b"), data.table(b=3L, d=4L))), data.table(a=1L, b=2L, b=3L, d=4L)) # key is wiped
+test(12.09, cbindlist(list(data.table(a=1L, b=2L), data.table(b=3L, d=4L))), data.table(a=1L, b=2L, b=3L, d=4L))
 local({
+  # also test that keys, indices are wiped
   ans = cbindlist(list(setindexv(data.table(a=2:1, b=1:2), "a"), data.table(a=1:2, b=2:1, key="a"), data.table(a=2:1, b=1:2)))
   test(12.10, ans, data.table(a=2:1, b=1:2, a=1:2, b=2:1, a=2:1, b=1:2))
   test(12.11, indices(ans), NULL)