Create new SVN repo locally and add a new Unity project to it as the first revision. Open the project in Unity. Save the default empty scene. Result:
UNITY -> c:add
add
UNITY -> 3
UNITY -> E:/elvisSVN/UnitySVN/Assets/
UNITY -> 1
UNITY -> E:/elvisSVN/UnitySVN/Assets/test.unity
UNITY -> 1
UNITY -> E:/elvisSVN/UnitySVN/Assets/test.unity.meta
UNITY -> 32769
"C:\Program Files\TortoiseSVN\bin\svn.exe" add --depth=empty "E:/elvisSVN/UnitySVN/Assets" "E:/elvisSVN/UnitySVN/Assets/test.unity" "E:/elvisSVN/UnitySVN/Assets/test.unity.meta"
Fatal 2: Failed to start process '"C:\Program Files\TortoiseSVN\bin\svn.exe" add --depth=empty "E:/elvisSVN/UnitySVN/Assets" "E:/elvisSVN/UnitySVN/Assets/test.unity" "E:/elvisSVN/UnitySVN/Assets/test.unity.meta"' exit code 1
e1:Failed to start process '"C:\Program Files\TortoiseSVN\bin\svn.exe" add --depth=empty "E:/elvisSVN/UnitySVN/Assets" "E:/elvisSVN/UnitySVN/Assets/test.unity" "E:/elvisSVN/UnitySVN/Assets/test.unity.meta"' exit code 1
r1:end of response