plugin/percol: `shellcheck` & `shfmt`

According to `shellcheck`, the `_tac` alias simply doesn't work. At all. Ever. See SC2262 and SC2263.

clean_files.txt

@@ -92,6 +92,7 @@ plugins/available/hub.plugin.bash
 plugins/available/jump.plugin.bash
 plugins/available/node.plugin.bash
 plugins/available/nodenv.plugin.bash
+plugins/available/percol.plugin.bash
 plugins/available/plenv.plugin.bash
 plugins/available/pyenv.plugin.bash
 plugins/available/rbenv.plugin.bash

plugins/available/percol.plugin.bash

@@ -25,14 +25,9 @@ fi
 
 function _replace_by_history() {
 	local HISTTIMEFORMAT= # Ensure we can parse history properly
-    if _command_exists tac
-	then
-        alias _tac=tac
-    else
-        alias _tac="tail -r"
-    fi
 	#TODO: "${histlines[@]/*( )+([[:digit:]])*( )/}"
-    local l="$(history | _tac | sed -e 's/^\ *[0-9]*\ *//' | percol --query "${READLINE_LINE:-}")"
+	local l
+	l="$(history | tail -r | sed -e 's/^\ *[0-9]*\ *//' | percol --query "${READLINE_LINE:-}")"
 	READLINE_LINE="${l}"
 	READLINE_POINT=${#l}
 }