source column-name missing when the input vector contains only one csv-file

[yakir12]

When files contains more than one csv-file name, the resulting table includes as expected and documented the chosen source column name:

tbl = CSV.File(files; source = :source)
@assert length(files) > 1
:source ∈ keys(first(tbl)) # true

But when the Vector files contains only one item, the resulting table does not.

tbl = CSV.File(files; source = :source)
@assert length(files) == 1
:source ∈ keys(first(tbl)) # false