fix parsing headers 48105b07

[kuk0]

see the comments in 48105b0
the two versions of isHeaderLine are not equivalent and the commit broke reading correct BED files

[38]

Why revert it? This is a critical optimization that makes it significantly faster.

[38]

I guess we could fix the parser - of course it has bug.

And please note, the original version isn't a reliable parsing code as well. The point is we need to handle most of the case.

[kuk0]

This is a critical optimization that makes it significantly faster.

ok, well, but how much faster? do you have a benchmark?
how many times is that function (isHeaderLine) called?
e.g., if i have a file with 1M lines, but the header is just the first line, i would expect it to be called ~ once or twice (then it would be unnecessary to optimize it at all); if it's called 1M times, is it necessary?

[kuk0]

i have updated the diff and tested it on this BED file:

chr	start	end	name	score	strand
NC_045512.2	0	29903	sars2	.	+

bedtools v2.29.2 can read this file
bedtools v2.30.0 is broken