Make annotate --follow an alias for -f/--file to behave like in older versions
Since 98a0421b9e52 annotate follows copies/renames by default, but the output
of e.g. "annotate --follow --number" should not change without some
deprecation time.
# should print nothing
# should fail
abort: path 'b/x' is inside repo 'b'
abort: path 'b/x' is inside repo 'b'
# should fail
abort: path 'b/x' is inside repo 'b'
# should arguably print nothing
# should fail
abort: path 'b/a' is inside repo 'b'