Setting "xwiki.authentication.cookielife" on a domain-based farm only works for the main wiki

Steps to reproduce:

• Set your farm to be domain-based
• Add the parameter "xwiki.authentication.cookielife=0.02" in "xwiki.cfg" which means that cookies will expire after 30 minutes.
• Login on the main wiki with "remember me" checked and you see that the cookies are correctly created for the domain ("raluca.com" in my case)
• Do the same on a sub-wiki and notice that the cookies are created for the domain of the main wiki ("raluca.com") and not for the domain which corresponds to the sub-wiki ("cookiesubwiki.raluca.com"). This way, after 30 minutes the session will not expire.