Calling coverage on a BAM re-fetches the header every time
Created by: ah19
A possible performance issue rather than a bug: https://github.com/Ensembl/Bio-DB-HTS/blob/master/lib/Bio/DB/HTS.pm#L1951
...
my $header = $self->{hts_file}->header_read;
my ( $id, $s, $e ) = $header->parse_region($region);
return unless defined $id;
# parse_region may return a very high value if no end specified
$end = $e >= 1 << 29 ? $header->target_len->[$id] : $e;
...
Calling $self->header
uses the cached version