API 2.0 commit diffstat always returns http 500 for the first commit of any hg repo

While developing highly requested feature of Awesome Graphs for Bitbucket Cloud we noticed that REST [{{/2.0/repositories/

/

/diffstat/

}}|https://developer.atlassian.com/bitbucket/api/2/reference/resource/repositories/%257Busername%257D/%257Brepo_slug%257D/diffstat/%257Bspec%257D] always returns http 500 for the first commit of any hg repo with the following JSON body:

{"type": "error", "error": {"message": "Something went wrong", "id": "f08d610fa13b49bdbdead955aa24c436"}}

Here is the list of public repositories with links to commits and API requests for you to reproduce this issue:

Repo 1 https://bitbucket.org/dayturn/dayturn

the first commit UI link: https://bitbucket.org/dayturn/dayturn/commits/003dd9461bfa479049afcc34545ab3431b147c7c

the first commit diffstat API req: https://bitbucket.org/api/2.0/repositories/%7B%7D%2F%7Bdaafc28d-027e-49a1-8f51-a6fbc5d243f5%7D/diffstat/003dd9461bfa479049afcc34545ab3431b147c7c

Repo 2 https://bitbucket.org/dzagorovsky/pypy-fork

the first commit UI link: https://bitbucket.org/dzagorovsky/pypy-fork/commits/45eff22199974f85fd96138d25510f4660aba5a1

the first commit diffstat API req: https://bitbucket.org/api/2.0/repositories/%7B%7D%2F%7B162486ca-97f7-4ba6-96f6-e11fd145a9bd%7D/diffstat/45eff22199974f85fd96138d25510f4660aba5a1

Also the same error returns for a commit in the middle of pypy repo:
Commit UI link: https://bitbucket.org/dzagorovsky/pypy-fork/commits/bf2c629d00711b091509f687151a057cf3098b13

Commit diffstat link: https://bitbucket.org/api/2.0/repositories/%7B%7D%2F%7B162486ca-97f7-4ba6-96f6-e11fd145a9bd%7D/diffstat/bf2c629d00711b091509f687151a057cf3098b13

We have tested API 2.0 commit diff stat with a bunch of our private and public hg repositories. The first hg repo commit diffstat always returns http 500.