Make displaying python version configurable

functions/fish_prompt.fish

@@ -33,6 +33,7 @@
 #     set -g theme_display_aws_vault_profile yes
 #     set -g theme_display_hg yes
 #     set -g theme_display_virtualenv no
+#     set -g theme_display_virtualenv_python_version no
 #     set -g theme_display_nix no
 #     set -g theme_display_ruby no
 #     set -g theme_display_user ssh
@@ -849,6 +850,9 @@ function __bobthefish_prompt_rubies -S -d 'Display current Ruby information'
 end
 
 function __bobthefish_virtualenv_python_version -S -d 'Get current Python version'
+    [ "$theme_display_virtualenv_python_version" = 'no' ]
+    and return
+
     switch (python --version 2>&1 | tr '\n' ' ')
         case 'Python 2*PyPy*'
             echo $pypy_glyph