14w25b to minecraft 1.7 sign glitch

If you downgrade a server from 14w25a to 1.7.10, sign numbers will be converted (like 0311 to /u0027) and blank lines on signs will be converted to "null" (Without quotes). Third, all sign lines (exept for the 'null' lines) will get quotes around them. I have a image of a ground sign in the photo, but wall signs will have the same effects.