Fix for duplicate names in list_recurse()

[mgirlich]

Currently, list_modify(), update_list() and list_merge() give wrong results when there are duplicate names in the dots argument, e.g.

list_modify(list(x = 1), x = 2, x = 3)
# actual result
#> $x
#> [1] 2

# expected result
#> $x
#> [1] 3

list_merge(list(x = 1), x = 2, x = 3)
# actual result
#> $x
#> [1] 1 2 2

# expected result
#> $x
#> [1] 1 2 3

In the above example it is of course not very useful. But when splicing with !!! this looks useful to me.
The pull request fixes the underlying function list_recurse() so that it handles duplicate names correctly.

[hadley]

Can you please add a bullet to NEWS? It should briefly describe the change (starting with name of the function), and crediting yourself with (@yourname, #issuenumber).

[mgirlich]

I just added the bullet in the NEWS. Is it okay like this?

[hadley]

Perfect, thanks!