404 error on View File for Commits with Spaces in File/Folder

[Svra44]

• Gitea version (or commit ref): 1.12.4
• Git version: 2.20.1
• Operating system: Debian 10.5
• 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:

gitea[10132]: [Macaron] 2020-09-16 22:45:50: Started GET /TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/th for 192.168.0.10
gitea[10132]: [Macaron] 2020-09-16 22:45:50: Completed GET /TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/th 404 Not Found in 4.921573ms

gitea[10132]: [Macaron] 2020-09-16 22:48:26: Started GET /TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/file%20with%20spaces.txt for 127.0.0.1
gitea[10132]: [Macaron] 2020-09-16 22:48:26: Completed GET /TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/file%20with%20spaces.txt 200 OK in 7.585426ms

Description

Gitea appears to incorrectly handle the "View File" option when viewing commits to files with spaces either in the file name, or in the containing directory structure.
Have tested in both FF 80.0.1 & Chromium 85.0.4183.102

When accessing a commit view, & selecting the "View File" option, it redirects to an incorrect link.
Example:

• Filename: "file with spaces.txt"
• "View File" link: http://127.0.0.1:3000/TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/th
  -- Result: 404
• Correct Link: http://127.0.0.1:3000/TestUser1/tmpGit/src/commit/23bfc188a8d3fed0156640551136192fbe2588d7/file%20with%20spaces.txt
  -- Result: 200 (page loads fine when manually browsing to this link)

Tested directly against gitea localhost:3000 bind, taking reverse proxy out of the chain.
Same git repo uploaded to try.gitea.io doesnt exhibit the same issue.

Screenshots

[mrsdizzie]

Duplicate of #12768 and should be fixed in 1.12.5 by #12776