Expectations:
line can be delimited with any standard delimiter ',' ';' '#'
header line should be processable too

CONTEXT:
Header line which cant be processed
Header 1;Header 2;Header 3;;Header 5;;Header 7

Apache parser interprets first ;; as empty header, but it swalows second ;; which causes problem in later output processing

We can check this together before I fix it. (My plan is to provide own parser for header if apache csv fails on this)
See pull:
#3289