feat(__load_completion): pass absolute path when sourcing and available

Mostly for better handling of completions loaded via relative paths, in
case the completion registers it for the exact command passed to it.

Author: scop

bash_completion

@@ -2508,6 +2508,13 @@ __load_completion()
         backslash=\\
     fi
 
+    # Try to resolve real path to $cmd, and make it absolute
+    local ret realcmd=
+    if _comp_realcommand "$cmd"; then
+        realcmd=$ret
+        cmd=${realcmd%/*}/$cmdname # basename could be an alias
+    fi
+
     local -a dirs=()
 
     # Lookup order:
@@ -2531,9 +2538,8 @@ __load_completion()
         dirs+=(./completions)
     fi
 
-    # 3) From bin directories extracted from $(realpath "$cmdname") and PATH
-    local ret
-    _comp_realcommand "$cmd" && paths=("${ret%/*}") || paths=()
+    # 3) From bin directories extracted from path to command, and $PATH
+    [[ $realcmd ]] && paths=("${realcmd%/*}") || paths=()
     _comp_split -aF : paths "$PATH"
     for dir in "${paths[@]%/}"; do
         if [[ -d $dir && $dir == ?*/@(bin|sbin) ]]; then