UnityYAMLMerge does not run with SourceTree

Hi, I'm Matthew, a newcomer with Unity 5.

I use

• Unity 5.6.1 (2017.1.0f3 ,64-bit)

• 64-bit Windows 10 desktop

• SourceTree 2.1.7

• Git 2.13

• P4Merge 2017.2

• Survival Shooter tutorial

and the tutorial project is configured to "Asset Serialization, Mode - Force Text". to test the "Smart Merge" feature.

In the Smart Merge doc, it mentions a configuration for SourceTree.

I have tried that configuration, but when I "diff" a file, the UnityYAMLMerge does not run.

Check my shared video, please; I recorded that nothing happens after configuring UnityYAMLMerge and executing "External Diff".

I also noticed that the ".gitconfig" file didn't change after configuring UnityYAMLMerge.

 [difftool "sourcetree"]
     cmd = 'C:/Program Files/Perforce/p4merge.exe' \"$LOCAL\" \"$REMOTE\"
 [mergetool "sourcetree"]
     cmd = 'C:/Program Files/Perforce/p4merge.exe' \"$BASE\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\"
     trustExitCode = true
 [user]
     email = matt@xxx.xxx
     name = MATTHEW_DESKTOP0

I thought the UnityYAMLMerge would be added to the ".gitconfig" file, but nothing happened.

Here is another video I have recorded; Although I have followed the UnityYAMLMerge configuration for SourceTree, P4Merge pops up.

 [core]
     repositoryformatversion = 0
     filemode = false
     bare = false
     logallrefupdates = true
     symlinks = false
     ignorecase = true
 [remote "origin"]
     url = https://gitlab.com/XXXXXX.git
     fetch = +refs/heads/*:refs/remotes/origin/*
 [user]
     name = MATTHEW_DESKTOP0
     email = matt@xxx.xxx

There was nothing related to UnityYAMLMerge in the ".git/config" file, either.

Is my configuration wrong?

• Diff Command: C:\Program Files\Unity\Editor\Data\Tools\UnityYAMLMerge.exe

• Arguments: merge -p $BASE $REMOTE $LOCAL $MERGED

• In mergespecfile.txt (fallout to P4Merge)

  unity use "C:\Program Files\Perforce\p4merge.exe" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"

  prefab use "C:\Program Files\Perforce\p4merge.exe" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"

ref. link

Is it impossible for UnityYAMLMerge to diff a previously committed file?

Or do I need to type something manually in the .gitconfig file?

-KIND REGARDS, MATTHEW