$ mkdir t
$ cd t
$ hg init
$ echo This is file a1 > a
$ echo This is file b1 > b
$ hg add a b
$ hg commit -m "commit #0" -d "1000000 0"
$ echo This is file b22 > b
$ hg commit -m"comment #1" -d "1000000 0"
$ hg update 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm b
$ hg commit -A -m"comment #2" -d "1000000 0"
removing b
created new head
$ mv a c
in theory, we shouldn't need the "-y" below, but it prevents
this test from hanging when "hg update" erroneously prompts the
user for "keep or delete"
should abort
$ hg update -y 1
abort: crosses branches (use 'hg merge' to merge or use 'hg update -C' to discard changes)
$ mv c a
should succeed
$ hg update -y 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ exit 0