Signs that placed in old versions are looking different in 15w31a. (They have " and / punctuations)

Old signs (before 15w31a) are looking different.

Example:

Sign in 1.8
__________
Hello world!

__________

the same sign in 1.9
__________
"/Hello world"/
"/"/"/
"/"/"/
__________

New sign that placed in 15w31a (it's a normal sign)
__________
Hello world

__________