Cannot build from source without repo

git clone https://github.com/apache/ratis.git
cd ratis
rm -fr .git
mvn -DskipTests clean package

[INFO] Apache Ratis ....................................... FAILURE [  0.890 s]
...
[ERROR] Failed to execute goal org.codehaus.mojo:buildnumber-maven-plugin:1.4:create-metadata (default) on project ratis: Execution default of goal org.codehaus.mojo:buildnumber-maven-plugin:1.4:create-metadata failed.: NullPointerException -> [Help 1]