see e.g. https://build.kde.org/job/kdevplatform%20master%20kf5-qt5/PLATFORM=Linux,compiler=gcc/55/testReport/(root)/TestSuite/test_kdevgit/

QDEBUG : GitInitTest::revHistory() kdevplatform.vcs: Execute dvcs command: "git symbolic-ref -q --short HEAD"
QDEBUG : GitInitTest::revHistory() kdevplatform.vcs: Execute dvcs command: "git rev-list master"
QDEBUG : GitInitTest::revHistory() kdevplatform.vcs: oops, found an error while running "git rev-list master" : "UnknownError" Exit code is: 128

this happens on a bare repository without any commits (due to another error). to reproduce try to run this e.g.:

cd /tmp
mkdir test
cd test
git init
git rev-list master
# fatal: ambiguous argument 'master': unknown revision or path not in the working tree.
# Use '--' to separate paths from revisions, like this:
# 'git <command> [<revision>...] -- [<file>...]'

this will then lead to the assert in the kdevelop code base

Reproducible: Always