FYI, I created a patch to enhance the plugin with a new string parameter called "Trac source repository browser prefix" (couldn't come up with a better name). You may enter any path into this textfield. The plugin will subtract this prefix from the URL before opening the Trac browser.

The online help for this new field needs more explanation.

dmoebius: Thanks a lot for creating this patch, looking forward to seeing a fix.

Code changed in jenkins
User: Gerd Zanker
Path:
pom.xml
src/main/java/hudson/plugins/trac/TracRepositoryBrowser.java
src/test/java/hudson/plugins/trac/TracSvnRepositoryBrowserTest.java
src/test/resources/hudson/plugins/trac/changelog-with-deleted-file.xml
src/test/resources/hudson/plugins/trac/changelog_unsorted.xml
http://jenkins-ci.org/commit/trac-plugin/70dbb9210b77cf46c76dc2330b7d8d6dabd6293e
Log:
Added test for existing subversion TracRepositoryBrowser class to have a
clean, tested base for JENKINS-7032 and JENKINS-13366

Merged with pull request #5 into trac master branch.

My Trac instance supports multiple Git repositories. The Trac 1.0.1 wiki "Start Page" is here:

https://server.my.org:8000/GIT_REPOS/wiki/WikiStart 

and the "Browse Source" button takes me to the Repository Index:

https://server.my.org:8000/GIT_REPOS/browser

This is very similar to the Trac 1.2.2 demo page at

https://trac.edgewall.org/demo-1.2/browser

When I configure the "Trac website" for my xy_code repository as follows:

https://server.my.org:8000/GIT_REPOS/browser/xy_code

the Jenkins project Trac link provides that link and that works as expected.

However, with TracGit selected as the "Repository browser" the TracGit links are not created correctly. An example, TracGit link from a Jenkins "Changes" page to a particular changeset incorrectly gives:

https://server.my.org:8000/GIT_REPOS /changeset/5c6e21f19164608b69aa205c014222f4b31e93bb

instead of the correct link:

https://server.my.org:8000/GIT_REPOS/changeset/5c6e21f19164608b69aa205c014222f4b31e93bb/xy_code

Again, the structure of my correct link is similar to the structure of a changeset link in the Trac 1.2.2 demo:

https://trac.edgewall.org/demo-1.2/changeset/16130/trac.svn

Using Jenkins 2.60.1 and Trac Plugin 1.13

I googled '"Powered by Trac 1.2" git' and followed the "Browse Source" links for several public Trac sites. It looks to me as if those sites that are NOT structured so as to have a "Default Repository" as well as a "Repository Index" on the top-level browser page are the sites that Jenkins is currently configured to support. See the differences, for example, for these two cases with svn repositories:

https://josm.openstreetmap.de/browser

https://josm.openstreetmap.de/changeset/12510/josm

vs.

https://trac.wildfiregames.com/browser

https://trac.wildfiregames.com/changeset/19137/

I'm pretty sure that the problem only occurs when using one of the repositories that is NOT considered the "Default Repository". There is a public git repository that allows demonstration of the problem at https://devel.rtems.org/ The rtems-docs repository is not the default repository, so I set the following two fields in the Jenkins configuration as follows:

Trac website: https://devel.rtems.org/

Repository URL: git://git.rtems.org/rtems-docs.git

Then for the changeset 5ffa072 Jenkins incorrectly generates this TracGit link:

https://devel.rtems.org/changeset/5ffa0722e449c780e07d4235d25b8c5356ee1797

instead of the correct:

https://devel.rtems.org/changeset/5ffa0722e449c780e07d4235d25b8c5356ee1797/rtems-docs