I just run conda update conda, and I found that I still update to 4.3.30, like follows:
user@user-Server:~/workspace$ conda update conda
Fetching package metadata …
Solving package specifications: .
All requested packages already installed.
packages in environment at /home/user/anaconda3:

conda                     4.3.30           py35hf9359ed_0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free 4
I think that maybe the conda updated from a mirror website.