Merge pull request #2366 from chuancong/patch-1

pip: Add support to command "show"

plugins/pip/_pip

@@ -20,6 +20,7 @@ _1st_arguments=(
   'bundle:create pybundles (archives containing multiple packages)'
   'freeze:output all currently installed packages (exact versions) to stdout'
   'help:show available commands'
+  'show:show information about installed packages'
   'install:install packages'
   'search:search PyPI'
   'uninstall:uninstall packages'
@@ -76,4 +77,7 @@ case "$words[1]" in
   uninstall)
     _pip_installed
     _wanted installed_pkgs expl 'installed packages' compadd -a installed_pkgs ;;
+  show)
+    _pip_installed
+    _wanted installed_pkgs expl 'installed packages' compadd -a installed_pkgs ;;
 esac