求助：ubuntu12.04下配置android环境下载android源码后出现的问题

Arctic_wang

在https://source.android.com/source/downloading.html网址上按照要求一步一步的完成，当下载完源代码后，
最后一行代码是$repo init -u https://android.googlesource.com/a/platform/manifest，之后还有
(1)using authentication(身份验证)，
(2)Troubleshooting network issues
$ export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
$ export HTTPS_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
$ sudo sysctl -w net.ipv4.tcp_window_scaling=0
$ repo sync -j1
执行到这里出现了许多的东西如：
………………
export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>error: Failed to connect to 2404:6800:4005:c00::52: Network is unreachable while accessing https://android.googlesource.com/platform/manifest/info/refs
fatal: HTTP request failed
export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
export HTTPS_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
error: The requested URL returned error: 406 while accessing https://android.googlesource.com/platform/manifest/info/refs
fatal: HTTP request failed
fatal: cannot obtain manifest https://android.googlesource.com/platform/manifest
cactus@arctic:~/android_src$ export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_portexport HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
bash: 未预期的符号 `newline' 附近有语法错误
cactus@arctic:~/android_src$ export HTTPS_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
bash: 未预期的符号 `newline' 附近有语法错误
cactus@arctic:~/android_src$ export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
bash: 未预期的符号 `newline' 附近有语法错误
cactus@arctic:~/android_src$ export HTTPS_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
bash: 未预期的符号 `newline' 附近有语法错误
cactus@arctic:~/android_src$ sudo sysctl -w net.ipv4.tcp_window_scaling=0
[sudo] password for cactus:
net.ipv4.tcp_window_scaling = 0
cactus@arctic:~/android_src$ repo sync -j1

... A new repo command ( 1.1 is available.
... You should upgrade soon:

    cp /home/cactus/android_src/.repo/repo/repo /home/cactus/bin/repo

remote: Counting objects: 32876, done
remote: Finding sources: 100% (22/22)
remote: Getting sizes: 100% (9/9)
remote: Compressing objects: 100% (9/9)
remote: Total 22 (delta 9), reused 19 (delta 9)
Unpacking objects: 100% (22/22), done.
From https://android.googlesource.com/platform/frameworks/base
   b1e16f1..b63e39a  master     -> aosp/master
remote: Counting objects: 7367, done
remote: Finding sources: 100% (36/36)
remote: Getting sizes: 100% (19/19)
remote: Compressing objects: 100% (19/19)
remote: Total 36 (delta 11), reused 34 (delta 11)
Unpacking objects: 100% (36/36), done.
From https://android.googlesource.com/platform/packages/apps/Settings
   f141594..7b8b661  master     -> aosp/master
remote: Counting objects: 597, done
remote: Finding sources: 100% (7/7)
停在了remote: Finding sources: 100% (7/7)不再执行，什么原因呢？