Added p4merge as mergetool in git config (only if OS is windows).

dot_gitconfig.tmpl

@@ -48,23 +48,41 @@
 
     # from pixelbeat
     brdate = for-each-ref --sort=-committerdate --format='%(committerdate:iso8601) %(refname:short)' refs/heads/
-	st = stash list --date=local
-	alias = ! git config --get-regexp ^alias\\. | sed -e s/^alias\\.// -e s/\\ /\\ =\\ /
-	d = diff -w
-	dc = diff -w --cached
+    st = stash list --date=local
+    alias = ! git config --get-regexp ^alias\\. | sed -e s/^alias\\.// -e s/\\ /\\ =\\ /
+    d = diff -w
+    dc = diff -w --cached
 
     # from https://www.toptal.com/developers/gitignore
     # create .gitignore templates based on operationg systems, IDE, languages etc.
     ignore = "!gi() { curl -sL https://www.toptal.com/developers/gitignore/api/$@ ;}; gi"
 
 [core]
-	editor = vim
+    editor = vim
 
 [push]
     # default = matching
     default = simple # safer option, push only current branch
+[pull]
+    ff = only
+
+{{ if eq .chezmoi.os "windows" -}}
 [merge]
     tool = p4merge
-	ff = false
-[pull]
-	ff = only
+    ff = false
+
+[mergetool "p4merge"]
+    path = "C:\\Program Files\\Perforce\\p4merge.exe"
+    cmd = p4merge $BASE $LOCAL $REMOTE $MERGED
+    keepBackup = false
+
+[difftool "p4merge"]
+    external = p4merge $LOCAL $REMOTE
+
+[difftool "winmerge"]
+    cmd = "'c:/PortableApps/PortableApps/WinMergePortable/App/WinMerge/WinMergeU'" -e "$LOCAL" "$REMOTE"
+
+{{ end -}}
+
+[http]
+    # proxy = http://host:port