Variant of findSplitBefore that destructively pops everything up to, not including, needle from haystack.
auto haystack = `xy`; const needle = `z`; auto pop = haystack.findPopBefore(needle); assert(haystack == `xy`); assert(pop == ``);
auto haystack = `xyz`; const needle = `y`; auto pop = haystack.findPopBefore(needle); assert(pop == `x`); assert(haystack == `yz`);
See Implementation
Variant of findSplitBefore that destructively pops everything up to, not including, needle from haystack.