Modify parse_cookies to split on first occurrence of '=' only

[rpkyle]

The parse_cookies function in request.R attempts to split cookies on each occurrence of =; this appears to generate errors such as the following when multiple instances of = occur within a cookie:

ERROR: 'names' attribute [11] must be the same length as the vector [10]

This may be reproduced by using curl or a similar tool to pass a cookie string containing two or more =, e.g.

curl -v -H "Cookie: a=1=2" 127.0.0.1:8050

The original lines are here:

reqres/R/request.R

Lines 437 to 445 in c69c053

	parse_cookies = function() {
	if (is.null(self$headers$Cookie)) return(list())
	cookies <- trimws(strsplit(self$headers$Cookie, ';')[[1]])
	cookies <- unlist(strsplit(cookies, '='))
	structure(
	as.list(url_decode(cookies[c(FALSE, TRUE)])),
	names = cookies[c(TRUE, FALSE)]
	)
	},

This pull request proposes to modify line 440:

cookies <- unlist(strsplit(sub("=", ";", cookies), ";"))

Since sub will only replace the first matching =, strsplit will split the line only once.

[alexcjohnson]

FWIW we encountered this issue in conjunction with google analytics, which creates cookies like:
__utmz=123456789.1234567890.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none);

[thomasp85]

I've opted to use stringi instead of substituting = with ; before the split. The outcome is the same though