Links in markdown should be absolute to the repository not the server

[zeripath]

Currently Gitea will render links like:

![/capybara.jpg/capybara-train.jpg](/capybara.jpg/capybara-train.jpg)
![capybara][capybara-train-jpg]

  [capybara-train-jpg]: /capybara.jpg/capybara-train.jpg

as being absolute with respect to the server when they should be relative to the repository prefix in order to be github compatible.

Fix #15075

⚠️ BREAKING ⚠️

This represents a change in the rendering of these links - however, it makes them match Github so the previous behaviour was a bug.

Signed-off-by: Andrew Thornton art27@cantab.net

[6543]

Can you add some unit tests?

[6543]

related: https://gitea.com/gitea/tea/pulls/332#issuecomment-314249
& charmbracelet/glamour#96 (comment)

[zeripath]

Ugh actually the situation is more complex indeed.

Take a look at https://github.com/zeripath/pathological/blob/master/README.md

[zeripath]

Fixed this! It should now replicate the GH way.

[lunny]

So the absolute path to site will break. I think we should mark this as break.

[zeripath]

Well... The current behaviour is a bug when compared to GitHub compatibility.

Do we know what gitlab does? If we can show that gitlab doesn't behave the same then we can probably make it a flag etc.

[6543]

gitlab example: https://gitlab.com/real6543/pathological/-/blob/master/README.md

[codecov-io]

Codecov Report

Merging #15088 (6ebcf69) into master (84f5a0b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #15088   +/-   ##
=======================================
  Coverage   43.93%   43.93%           
=======================================
  Files         677      677           
  Lines       81332    81332           
=======================================
  Hits        35732    35732           
+ Misses      39804    39799    -5     
- Partials     5796     5801    +5     

Impacted Files	Coverage Δ
modules/markup/markdown/goldmark.go	58.22% <100.00%> (ø)
modules/git/repo_base_nogogit.go	63.63% <0.00%> (-9.10%)	⬇️
modules/indexer/stats/db.go	48.00% <0.00%> (-8.00%)	⬇️
modules/git/utils.go	77.77% <0.00%> (-2.78%)	⬇️
modules/log/file.go	73.80% <0.00%> (-1.59%)	⬇️
modules/queue/unique_queue_disk_channel.go	53.73% <0.00%> (-1.50%)	⬇️
models/issue_comment.go	52.16% <0.00%> (-0.58%)	⬇️
services/pull/pull.go	43.30% <0.00%> (-0.49%)	⬇️
models/error.go	38.58% <0.00%> (-0.48%)	⬇️
modules/git/blame.go	67.14% <0.00%> (+1.42%)	⬆️
... and 4 more

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[silverwind]

Any reason not to backport this to 1.14?