Cannot run integration tests on git 1.7.2, 1.8.0, 2.1.2+

[zeripath]

• Gitea version (or commit ref): master
• Git version: 1.7.2, 1.8.0, 2.1.2
• Operating system:
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:

Description

We cannot run the gitea integration tests locally on early gits due to a number of issues:

• For git 1.7.2 there are multiple issues in Gitea no longer works on git 1.7.2 #7862
• For git < 2.1.2 integration tests expect LFS to run
• For git < 2.3.0 integrations tests requiring SSH won't work because GIT_SSH_COMMAND doesn't exist - we need to use GIT_SSH instead.
• For git > 2.0.0 to some version of git TestDeleteRepoFile will not work due to commit-tree signing by default - this will need to have --no-gpg-sign passed in.
• There's also an issue with the merge - in that the behaviour of fetch etc are different in git < 2.0.0