Given a simple repository

repo
a/Validator.java

Precondition
Branches master and feature/f1. feature/f1 branches from master. File Validator.java was modified in branch feature/f1 (23f27c), and in branch master moved from a/Validator.java to a/a2/a3/Validator.java (4128b7). A pull request was successful created from feature/f1 to master.

Error 1
In pull request TAB "Diff" the file is shown with destination path a/a2/a3. Is this the right behaviour? But file diffs are correct shown.

But after button "View the full source of this file"

is pressed, the warning "The path "a/a2/a3/Validator.java" does not exist at revision "refs/heads/feature/f1"" is printed.

With debug and trace enabled, we can see the git commands:

git for-each-ref --sort=-objecttype --format=%(objecttype)%02%(refname)%02%(objectname)%02%(*objectname) refs/heads/ refs/tags/
git cat-file -t refs/heads/feature/f1:a/a2/a3/Validator.java

In the 2nd command, the a/a2/a3/Validator.java doesn't match to branch feature/f1.

Error 2
Using a merge hook (MergeRequestCheck implementation), the methode contentService.streamFile() has the same problem, which leads to an Exception:

com.atlassian.stash.exception.NoSuchPathException: The path "a/a2/a3/Validator.java" does not exist at revision "23f27cf991c70ee70da1a553cd1f9654776ba744"

Where the last commit id got by

String latestCommitId = mergeRequest.getPullRequest().getFromRef().getLatestChangeset();

The resulting git command is

git cat-file -p 23f27cf991c70ee70da1a553cd1f9654776ba744:a/a2/a3/Validator.java

These both errors are present in our production stash 2.12.1 as well as in 3.8.0.
They can be avoided by an update of the source-branch with the destination branch.
But I think the API should handle this properly.