Add a test and CHANGELOG fix for #9096

CHANGELOG.rst

@@ -19,6 +19,7 @@ Interactive improvements
 - If the terminal definition for $TERM can't be used, fish now tries using the "xterm-256color" and "xterm" definitions before "ansi" and "dumb". As the majority of terminal emulators in common use are now more or less xterm-compatible (often even explicitly claiming the xterm-256color entry), this should often result in a fully or almost fully usable terminal (:issue:`9026`).
 - The history search text for a token search is now highlighted correctly if the line contains multiple instances of that text.
 - The new environment variable ``$fish_cursor_selection_mode`` can be used to configure whether the command line selection includes (``inclusive``) the character under the cursor or not (``exclusive``). The new default is ``exclusive``. Use ``set fish_cursor_selection_mode inclusive`` to get the previous behavior back (:issue:`7762`).
+- process-exit and job-exit events are now generated for all background jobs, including those launched from event handlers (:issue:`9096`).
 
 New or improved bindings
 ^^^^^^^^^^^^^^^^^^^^^^^^

tests/checks/wait.fish

@@ -56,3 +56,14 @@ end
 wait
 # CHECK: P1 over
 # CHECK: P2 over
+
+# Events for background jobs from event handlers (#9096)
+function __test_background_job_exit_event --on-variable trigger_var
+    sleep .1 &
+    function callback --on-process-exit (jobs --last --pid)
+        echo -n "Callback called"
+    end
+end
+set trigger_var 123
+sleep .5
+# CHECK: Callback called