Metrics in output thresholds.bed reports less coverage than BAM file
Hi !
Excellent tool! Thank you! 
I have an issue with the output thresholds.bed

In the sample X_S5 we found a variant (observed in the table), with a depth of 199+54 reported. However, the "thresholds.bed" show 0 bases in this block to 200X.

Tumor_Sample_Barcode | Chromosome | Start_Position | End_Position | Reference_Allele | Tumor_Seq_Allele2 | Hugo_Symbol | DP_ALT | DP_REF
-- | -- | -- | -- | -- | -- | -- | -- | --
X_S5 | chr12 | 25398284 | 25398284 | C | T | KRAS | 54 | 199

* commad line
```
mosdepth -b $HG19_Onco_bed  -T 100,200,300,400,500,600,700,800,900,1000 $output_mosdepth $dedup_resorted_bam
```
* In the output ``` X_S5.mosdepth.thresholds.bed``` , 0 bases are observed with a minimum of 200X in the region ```KRAS-EXON-2-MUTATION``` 

```
#chrom	start	end	region	100X	200X	300X	400X	500X	600X	700X	800X	900X	1000X
chr12	25398193	25398344	KRAS-EXON-2-MUTATION	138	0	0	0	0	0	0	0	0	0
```

* IGV in the position chr12  25,398,284. depth over 200
<img width="1101" alt="Captura de Pantalla 2021-10-14 a la(s) 21 15 43" src="https://user-images.githubusercontent.com/37847170/137412432-282a1571-b264-4176-b04c-a30650db8fe5.png">

```
mosdepth --version
mosdepth 0.2.5
```

