[bash] Revert skipping setting up fuzzy path completion

This partially reverts a2d0e8f not to break backward compatibility.

shell/completion.bash

@@ -496,18 +496,21 @@ __fzf_default_completion() {
   fi
 }
 
-if complete | command grep -q __fzf_default_completion; then
-  : # Default completion already set up. Do nothing.
-elif ! complete | command grep -- '-D$' | command grep -qv _comp_complete_load &&
-       complete -D -F __fzf_default_completion -o default -o bashdefault 2> /dev/null; then
-  a_cmds=""
-else
+# Set fuzzy path completion as the default completion for all commands.
 # We can't set up default completion,
 # 1. if it's already set up by another script
 # 2. or if the current version of bash doesn't support -D option
-  #
+complete | command grep -q __fzf_default_completion ||
+  complete | command grep -- '-D$' | command grep -qv _comp_complete_load ||
+  complete -D -F __fzf_default_completion -o default -o bashdefault 2> /dev/null
+
+d_cmds="${FZF_COMPLETION_DIR_COMMANDS-cd pushd rmdir}"
+
 # NOTE: $FZF_COMPLETION_PATH_COMMANDS and $FZF_COMPLETION_VAR_COMMANDS are
 # undocumented and subject to change in the future.
+#
+# NOTE: Although we have default completion, we still need to set up completion
+# for each command in case they already have completion set up by another script.
 a_cmds="${FZF_COMPLETION_PATH_COMMANDS-"
   awk bat cat code diff diff3
   emacs emacsclient ex file ftp g++ gcc gvim head hg hx java
@@ -517,10 +520,6 @@ else
   find git grep gunzip gzip hg jar
   ln ls mv open rm rsync scp
   svn tar unzip zip"}"
-fi
-
-d_cmds="${FZF_COMPLETION_DIR_COMMANDS-cd pushd rmdir}"
-
 v_cmds="${FZF_COMPLETION_VAR_COMMANDS-export unset printenv}"
 
 # Preserve existing completion