这个问题解决方法很简单，把Gitlab自带的nginx的配置文件复制到自己的nginx配置里面，稍作修改就可以了。Gitlab自带的nginx配置文件位于 /var/opt/gitlab/nginx/conf/gitlab-http.conf

文件内容如下

# This file is managed by gitlab-ctl. Manual changes will be
# erased! To change the contents below, edit /etc/gitlab/gitlab.rb
# and run `sudo gitlab-ctl reconfigure`.

## GitLab
## Modified from https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/support/nginx/gitlab-ssl & https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/support/nginx/gitlab
##
## Lines starting with two hashes (##) are comments with information.
## Lines starting with one hash (#) are configuration parameters that can be uncommented.
##
##################################
##        CHUNKED TRANSFER      ##
##################################
##
## It is a known issue that Git-over-HTTP requires chunked transfer encoding [0]
## which is not supported by Nginx < 1.3.9 [1]. As a result, pushing a large object
## with Git (i.e. a single large file) can lead to a 411 error. In theory you can get
## around this by tweaking this configuration file and either:
## - installing an old version of Nginx with the chunkin module [2] compiled in, or
## - using a newer version of Nginx.
##
## At the time of writing we do not know if either of these theoretical solutions works.
## As a workaround users can use Git over SSH to push large files.
##
## [0] https://git.kernel.org/cgit/git/git.git/tree/Documentation/technical/http-protocol.txt#n99
## [1] https://github.com/agentzh/chunkin-nginx-module#status
## [2] https://github.com/agentzh/chunkin-nginx-module
##
###################################
##         configuration         ##
###################################

upstream gitlab-workhorse {
  server unix:/var/opt/gitlab/gitlab-workhorse/socket;
}


server {
  listen *:80;


  server_name bw-server;
  server_tokens off; ## Don't show the nginx version number, a security best practice

  ## Increase this if you want to upload large attachments
  ## Or if you want to accept large git objects over http
  client_max_body_size 0;


  ## Real IP Module Config
  ## http://nginx.org/en/docs/http/ngx_http_realip_module.html

  ## HSTS Config
  ## https://www.nginx.com/blog/http-strict-transport-security-hsts-and-nginx/
  add_header Strict-Transport-Security "max-age=31536000";

  ## Individual nginx logs for this GitLab vhost
  access_log  /var/log/gitlab/nginx/gitlab_access.log gitlab_access;
  error_log   /var/log/gitlab/nginx/gitlab_error.log;

  if ($http_host = "") {
    set $http_host_with_default "bw-server";
  }

  if ($http_host != "") {
    set $http_host_with_default $http_host;
  }

  ## If you use HTTPS make sure you disable gzip compression
  ## to be safe against BREACH attack.


  ## https://github.com/gitlabhq/gitlabhq/issues/694
  ## Some requests take more than 30 seconds.
  proxy_read_timeout      3600;
  proxy_connect_timeout   300;
  proxy_redirect          off;
  proxy_http_version 1.1;

  proxy_set_header Host $http_host_with_default;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection $connection_upgrade;
  proxy_set_header X-Forwarded-Proto http;

  location / {
    proxy_cache off;
    proxy_pass  http://gitlab-workhorse;
  }

  location /assets {
    proxy_cache gitlab;
    proxy_pass  http://gitlab-workhorse;
  }

  error_page 404 /404.html;
  error_page 422 /422.html;
  error_page 500 /500.html;
  error_page 502 /502.html;
  location ~ ^/(404|422|500|502)(-custom)?\.html$ {
    root /opt/gitlab/embedded/service/gitlab-rails/public;
    internal;
  }


}

稍作修改成下面这样

# This file is managed by gitlab-ctl. Manual changes will be
# erased! To change the contents below, edit /etc/gitlab/gitlab.rb
# and run `sudo gitlab-ctl reconfigure`.

## GitLab
## Modified from https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/support/nginx/gitlab-ssl & https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/support/nginx/gitlab
##
## Lines starting with two hashes (##) are comments with information.
## Lines starting with one hash (#) are configuration parameters that can be uncommented.
##
##################################
##        CHUNKED TRANSFER      ##
##################################
##
## It is a known issue that Git-over-HTTP requires chunked transfer encoding [0]
## which is not supported by Nginx < 1.3.9 [1]. As a result, pushing a large object
## with Git (i.e. a single large file) can lead to a 411 error. In theory you can get
## around this by tweaking this configuration file and either:
## - installing an old version of Nginx with the chunkin module [2] compiled in, or
## - using a newer version of Nginx.
##
## At the time of writing we do not know if either of these theoretical solutions works.
## As a workaround users can use Git over SSH to push large files.
##
## [0] https://git.kernel.org/cgit/git/git.git/tree/Documentation/technical/http-protocol.txt#n99
## [1] https://github.com/agentzh/chunkin-nginx-module#status
## [2] https://github.com/agentzh/chunkin-nginx-module
##
###################################
##         configuration         ##
###################################

upstream gitlab-workhorse {
  server unix:/var/opt/gitlab/gitlab-workhorse/socket;
}


server {
  listen *:80;


  server_name git.bwbot.org;
  server_tokens off; ## Don't show the nginx version number, a security best practice

  ## Increase this if you want to upload large attachments
  ## Or if you want to accept large git objects over http
  client_max_body_size 0;


  ## Real IP Module Config
  ## http://nginx.org/en/docs/http/ngx_http_realip_module.html

  ## HSTS Config
  ## https://www.nginx.com/blog/http-strict-transport-security-hsts-and-nginx/
  add_header Strict-Transport-Security "max-age=31536000";

  ## Individual nginx logs for this GitLab vhost
  access_log  /var/log/gitlab/nginx/gitlab_access.log;
  error_log   /var/log/gitlab/nginx/gitlab_error.log;

  if ($http_host = "") {
    set $http_host_with_default "git.bwbot.org";
  }

  if ($http_host != "") {
    set $http_host_with_default $http_host;
  }

  ## If you use HTTPS make sure you disable gzip compression
  ## to be safe against BREACH attack.


  ## https://github.com/gitlabhq/gitlabhq/issues/694
  ## Some requests take more than 30 seconds.
  proxy_read_timeout      3600;
  proxy_connect_timeout   300;
  proxy_redirect          off;
  proxy_http_version 1.1;

  proxy_set_header Host $http_host_with_default;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header Upgrade $http_upgrade;
  #proxy_set_header Connection $connection_upgrade;
  proxy_set_header X-Forwarded-Proto http;

  location / {
    proxy_cache off;
    proxy_pass  http://gitlab-workhorse;
  }

  location /assets {
    #proxy_cache gitlab;
    proxy_pass  http://gitlab-workhorse;
  }

  error_page 404 /404.html;
  error_page 422 /422.html;
  error_page 500 /500.html;
  error_page 502 /502.html;
  location ~ ^/(404|422|500|502)(-custom)?\.html$ {
    root /opt/gitlab/embedded/service/gitlab-rails/public;
    internal;
  }


}

把上面的host name改成自己的就可以了。然后把文件保存在/etc/nginx/sites-enabled。下面重启nginx服务就可以了。

sudo nginx -s reload

这样WebIDE的文件就可以正常显示了