plugins/hub: use `_command_exists`

Addresses bash-it/bash-it#1632

clean_files.txt

@@ -86,6 +86,7 @@ plugins/available/goenv.plugin.bash
 plugins/available/history-search.plugin.bash
 plugins/available/history-substring-search.plugin.bash
 plugins/available/history.plugin.bash
+plugins/available/hub.plugin.bash
 plugins/available/jump.plugin.bash
 plugins/available/node.plugin.bash
 plugins/available/textmate.plugin.bash

plugins/available/hub.plugin.bash

@@ -1,4 +1,7 @@
+# shellcheck shell=bash
 cite about-plugin
 about-plugin 'load hub, if you are using it'
 
-command -v hub &> /dev/null && eval "$(hub alias -s)"
+if _command_exists hub; then
+	eval "$(hub alias -s)"
+fi