Point to the canonical Python repository

BitBucket mirror is no longer up to date with the canonical repository.

Fixes https://github.com/yyuu/pyenv/issues/409.

plugins/python-build/share/python-build/3.5-dev

@@ -1,3 +1,3 @@
 #require_gcc
 install_package "readline-6.3" "http://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
-install_hg "Python-3.5-dev" "https://bitbucket.org/mirror/cpython" "default" standard verify_py35 ensurepip
+install_hg "Python-3.5-dev" "https://hg.python.org/cpython" "default" standard verify_py35 ensurepip