Tests were failing for latest version of samtools available from github, which reports lowered
quality scores (0="!") in mpileup and tview for some isolated bases.  I will inquire with the
samtools folks to see if this is a bug or a feature, but in the meantime, it should be no problem
to pass tests for either version of samtools and allow installation.
Forgot to update bam index files when I reformatted BAM file to avoid header error.