completions/git: Rely on local completion

Co-authored-by: Koichi Murase <myoga.murase@gmail.com>

completions/git.completion.bash

@@ -0,0 +1,27 @@
+# bash completion support for Git.
+
+if ! _omb_util_function_exists __gitdir; then
+    is_completion_loaded=0
+    for path in $(type -aP git);
+    do
+        path="${path%/git}"
+        prefix="${path%/bin}"
+        # echo "[debug] Checking $prefix"
+        for file in share/bash-completion/completions/git share/git-core/contrib/completion/git-completion.bash;
+        do
+            _file="$prefix/$file"
+            if [[ -f $_file && -r $_file ]]; then
+                echo "[debug] Loading $_file"
+                is_completion_loaded=1
+                source "$_file"
+                break 2
+            fi
+        done
+    done
+    if [[ $is_completion_loaded == 0 ]]; then
+        # echo "[debug] No completion found: fallbacking"
+        source "$OSH/tools/git-completion.bash"
+    fi
+# else
+#    echo "[debug] __gitdir is a defined function: doing nothing"
+fi