Error getting comments by API

[jzrebiec]

• Gitea version (or commit ref): master build from 12.01.2017
• Git version: 2.7.4
• Operating system: Kubuntu 16.04
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:
  [Macaron] 2017-01-13 14:04:39: Started GET /api/v1/repos/:user/:repo/issues/comments?page=1&per_page=100 for 127.0.0.1
  2017/01/13 14:04:39 [D] Session ID: b524ae117632e0ec
  2017/01/13 14:04:39 [D] CSRF Token: ywVMzeEmcATmyrrK5W-2pdg01ZM6MTQ4NDMxMjY3OTgxNDYzMDM5MQ==
  [Macaron] 2017-01-13 14:04:39: Completed /api/v1/repos/:user/:repo/issues/comments?page=1&per_page=100 500 Internal Server Error in 26.69987ms
  2017/01/13 14:04:39 [...epo/issue_comment.go:52 ListRepoIssueComments()] [E] GetCommentsByRepoIDSince: Error 1052: Column 'created_unix' in order clause is ambiguous

Description

When using url: /api/v1/repos/:user/:repo/issues/comments
I am getting error:
{"message":"Error 1052: Column 'created_unix' in order clause is ambiguous","url":"https://godoc.org/github.com/go-gitea/go-sdk/gitea"}
...

[ethantkoenig]

I get the same error with PostgreSQL. I believe it's because both the issue and comment tables have a created_unix column.

[ethantkoenig]

@jzrebiec I've created a PR (#665) which fixes the problem for me. Can you confirm that it works for you as well?