[rkj-repos] Check for 'hg prompt' and exit if not found (#6655)

* Check for  extension, and exit if not found. Addresses #6036

* Fix styles in rkj-repos.theme

themes/rkj-repos.zsh-theme

@@ -1,6 +1,9 @@
-# user, host, full path, and time/date
-# on two lines for easier vgrepping
-# entry in a nice long thread on the Arch Linux forums: http://bbs.archlinux.org/viewtopic.php?pid=521888#p521888
+# user, host, full path, and time/date on two lines for easier vgrepping
+
+if ! grep -q "prompt" ~/.hgrc; then 
+  echo "This theme requires 'hg prompt' (https://bitbucket.org/sjl/hg-prompt/overview)"
+  return 1
+fi
 
 function hg_prompt_info {
     hg prompt --angle-brackets "\
@@ -33,4 +36,3 @@ function retcode() {}
 PROMPT=$'%{$fg_bold[blue]%}┌─[%{$fg_bold[green]%}%n%b%{$fg[black]%}@%{$fg[cyan]%}%m%{$fg_bold[blue]%}]%{$reset_color%} - %{$fg_bold[blue]%}[%{$fg_bold[white]%}%~%{$fg_bold[blue]%}]%{$reset_color%} - %{$fg_bold[blue]%}[%b%{$fg[yellow]%}'%D{"%Y-%m-%d %I:%M:%S"}%b$'%{$fg_bold[blue]%}]
 %{$fg_bold[blue]%}└─[%{$fg_bold[magenta]%}%?$(retcode)%{$fg_bold[blue]%}] <$(mygit)$(hg_prompt_info)>%{$reset_color%} '
 PS2=$' \e[0;34m%}%B>%{\e[0m%}%b '
-