Bug in unique

[gevro]

Hi,
There is a bug in the unique function on granges. First reported here:
https://www.biostars.org/p/386553/

Just be aware that unique() will ignore the data in the GRanges mcols

a_gr <- GRanges(seqnames = 1,
            ranges = IRanges(start=c(1,1),
                             end =c(2,2)), 
            strand=c("+"),
            other=c("a","b"))
a_gr
#GRanges object with 2 ranges and 1 metadata column:
#  seqnames    ranges strand |       other
#   <Rle> <IRanges>  <Rle> | <character>
#[1]        1       1-2      + |           a
#[2]        1       1-2      + |           b

unique(a_gr)
#GRanges object with 1 range and 1 metadata column:
#seqnames    ranges strand |       other
#   <Rle> <IRanges>  <Rle> | <character>
#[1]        1       1-2      + |           a

unique should either: 1) take into account all mcols, or 2) the result should not have any mcols.

Returning a result with mcols when the function does not take it into account is misleading and could lead to undetectable bugs.