[ENSCORESW-922]. Problem with circular chromosomes when feature start/end wrt slice are negative. The computation of min_start/max_end is not reliable in this case, so I've added an extra condition testing whether the relateive coordinates are positive. When there are negative coordinates, the recomputed slice boundaries will not represent the exact extent of the region spanned by the transcript, but this shouldn't be a problem so all transcript IDs are included in the following fetch_all_by_Slice query.
[ENSCORESW-922]. Problem with circular chromosomes when feature start/end wrt slice are negative.
The computation of min_start/max_end is not reliable in this case, so I've added an extra condition
testing whether the relateive coordinates are positive.
When there are negative coordinates, the recomputed slice boundaries will not represent the exact
extent of the region spanned by the transcript, but this shouldn't be a problem so all transcript
IDs are included in the following fetch_all_by_Slice query.

james-monkeyshines/ensembl,at7/ensembl,james-monkeyshines/ensembl,Ensembl/ensembl,muffato/ensembl,james-monkeyshines/ensembl,mjg17/ensembl,danstaines/ensembl,james-monkeyshines/ensembl,at7/ensembl,Ensembl/ensembl,mjg17/ensembl,Ensembl/ensembl,muffato/ensembl,muffato/ensembl,danstaines/ensembl,muffato/ensembl,at7/ensembl,mjg17/ensembl,mjg17/ensembl,at7/ensembl,danstaines/ensembl,Ensembl/ensembl