Remove setup outside of fish_prompt from sample prompts

This doesn't work with fish_config.

For terlar and pythonista, remove unnecessary color setting.

For informative+git and pythonista, move variable setup into fish_prompt

Fixes #1141

share/tools/web_config/sample_prompts/informative_git.fish

@@ -1,29 +1,63 @@
 # name: Informative Git Prompt
 # author: Mariusz Smykula <mariuszs at gmail.com>
 
-set -g __fish_git_prompt_show_informative_status 1
-set -g __fish_git_prompt_hide_untrackedfiles 1
-
-set -g __fish_git_prompt_color_branch magenta --bold
-set -g __fish_git_prompt_showupstream "informative"
-set -g __fish_git_prompt_char_upstream_ahead "↑"
-set -g __fish_git_prompt_char_upstream_behind "↓"
-set -g __fish_git_prompt_char_upstream_prefix ""
-
-set -g __fish_git_prompt_char_stagedstate "●"
-set -g __fish_git_prompt_char_dirtystate "✚"
-set -g __fish_git_prompt_char_untrackedfiles "…"
-set -g __fish_git_prompt_char_conflictedstate "✖"
-set -g __fish_git_prompt_char_cleanstate "✔"
-
-set -g __fish_git_prompt_color_dirtystate blue
-set -g __fish_git_prompt_color_stagedstate yellow
-set -g __fish_git_prompt_color_invalidstate red
-set -g __fish_git_prompt_color_untrackedfiles $fish_color_normal
-set -g __fish_git_prompt_color_cleanstate green --bold
 
 
 function fish_prompt --description 'Write out the prompt'
+	if not set -q __fish_git_prompt_show_informative_status
+		set -g __fish_git_prompt_show_informative_status 1
+	end
+	if not set -q __fish_git_prompt_hide_untrackedfiles
+		set -g __fish_git_prompt_hide_untrackedfiles 1
+	end
+
+	if not set -q __fish_git_prompt_color_branch
+		set -g __fish_git_prompt_color_branch magenta --bold
+	end
+	if not set -q __fish_git_prompt_showupstream
+		set -g __fish_git_prompt_showupstream "informative"
+	end
+	if not set -q __fish_git_prompt_char_upstream_ahead
+		set -g __fish_git_prompt_char_upstream_ahead "↑"
+	end
+	if not set -q __fish_git_prompt_char_upstream_behind
+		set -g __fish_git_prompt_char_upstream_behind "↓"
+	end
+	if not set -q __fish_git_prompt_char_upstream_prefix
+		set -g __fish_git_prompt_char_upstream_prefix ""
+	end
+
+	if not set -q __fish_git_prompt_char_stagedstate
+		set -g __fish_git_prompt_char_stagedstate "●"
+	end
+	if not set -q __fish_git_prompt_char_dirtystate
+		set -g __fish_git_prompt_char_dirtystate "✚"
+	end
+	if not set -q __fish_git_prompt_char_untrackedfiles
+		set -g __fish_git_prompt_char_untrackedfiles "…"
+	end
+	if not set -q __fish_git_prompt_char_conflictedstate
+		set -g __fish_git_prompt_char_conflictedstate "✖"
+	end
+	if not set -q __fish_git_prompt_char_cleanstate
+		set -g __fish_git_prompt_char_cleanstate "✔"
+	end
+
+	if not set -q __fish_git_prompt_color_dirtystate
+		set -g __fish_git_prompt_color_dirtystate blue
+	end
+	if not set -q __fish_git_prompt_color_stagedstate
+		set -g __fish_git_prompt_color_stagedstate yellow
+	end
+	if not set -q __fish_git_prompt_color_invalidstate
+		set -g __fish_git_prompt_color_invalidstate red
+	end
+	if not set -q __fish_git_prompt_color_untrackedfiles
+		set -g __fish_git_prompt_color_untrackedfiles $fish_color_normal
+	end
+	if not set -q __fish_git_prompt_color_cleanstate
+		set -g __fish_git_prompt_color_cleanstate green --bold
+	end
 
 	set -l last_status $status
 

share/tools/web_config/sample_prompts/pythonista.fish

@@ -1,15 +1,11 @@
 # name: Simple Pythonista
 # author: davbo
 
-set normal (set_color normal)
-set magenta (set_color magenta)
-set yellow (set_color yellow)
-set green (set_color green)
-set gray (set_color -o black)
-
-set -g VIRTUAL_ENV_DISABLE_PROMPT true
 
 function fish_prompt
+   if not set -q VIRTUAL_ENV_DISABLE_PROMPT
+      set -g VIRTUAL_ENV_DISABLE_PROMPT true
+   end
    set_color yellow
    printf '%s' (whoami)
    set_color normal

share/tools/web_config/sample_prompts/terlar.fish

@@ -1,9 +1,6 @@
 # name: Terlar
 # author: terlar - https://github.com/terlar
 
-set -g fish_color_user magenta
-set -g fish_color_host yellow
-
 function fish_prompt --description 'Write out the prompt'
   set -l last_status $status