Exclude autojump from the background job count

Apparently it is super annoying and not really useful, since it executes in the background every time you change directories, so there is always a "background job" right when the prompt is rendered.

This relies on the AUTOJUMP_SOURCED environment variable to opt users into this behavior, since it would be a bit slower for every user every time we render the prompt.

Fixes #169

fish_prompt.fish

@@ -422,13 +422,24 @@ function __bobthefish_prompt_status -S -a last_status -d 'Display flags for a no
     and set superuser 1
 
     # Jobs display
-    if [ "$theme_display_jobs_verbose" = 'yes' ]
-        set bg_jobs (jobs -p | wc -l)
+    if set -q AUTOJUMP_SOURCED
+        # Autojump special case: check if there are jobs besides the `autojump`
+        # job, since that one is (briefly) backgrounded every time we `cd`
+        set bg_jobs (jobs -c | string match -v --regex '(Command|autojump)' | wc -l)
         [ "$bg_jobs" -eq 0 ]
         and set bg_jobs # clear it out so it doesn't show when `0`
     else
-        jobs -p >/dev/null
-        and set bg_jobs 1
+        if [ "$theme_display_jobs_verbose" = 'yes' ]
+            set bg_jobs (jobs -p | wc -l)
+            [ "$bg_jobs" -eq 0 ]
+            and set bg_jobs # clear it out so it doesn't show when `0`
+        else
+            # `jobs -p` is faster if we redirect to /dev/null, because it exits
+            # after the first match. We'll use that unless the user wants to
+            # display the actual job count
+            jobs -p >/dev/null
+            and set bg_jobs 1
+        end
     end
 
     if [ "$nonzero" -o "$superuser" -o "$bg_jobs" ]
@@ -679,7 +690,8 @@ function __bobthefish_prompt_user -S -d 'Display current user and hostname'
     end
 
     if set -q display_hostname
-        if set -q display_user; or set -q display_sudo_user
+        if set -q display_user
+            or set -q display_sudo_user
             # reset colors without starting a new segment...
             # (so we can have a bold username and non-bold hostname)
             set_color normal