Make job_control a constant property of job_t

It no longer changes.

src/exec.cpp

@@ -918,12 +918,6 @@ bool exec_job(parser_t &parser, const shared_ptr<job_t> &j, const job_lineage_t
     // Check to see if we should reclaim the foreground pgrp after the job finishes or stops.
     const bool reclaim_foreground_pgrp = (tcgetpgrp(STDIN_FILENO) == pgrp);
 
-    // If we are running nested inside a function or block with job control, then we need job
-    // control too.
-    if (lineage.root_has_job_control) {
-        j->mut_flags().job_control = true;
-    }
-
     // Perhaps we know our pgroup already.
     assert(j->pgid == INVALID_PID && "Should not yet have a pid.");
     switch (j->pgroup_provenance) {

src/parse_execution.cpp

@@ -1273,12 +1273,12 @@ end_execution_reason_t parse_execution_context_t::run_1_job(tnode_t<g::job> job_
     props.skip_notification =
         ld.is_subshell || ld.is_block || ld.is_event || !parser->is_interactive();
     props.from_event_handler = ld.is_event;
+    props.job_control = wants_job_control;
 
     shared_ptr<job_t> job = std::make_shared<job_t>(acquire_job_id(), props, this->lineage);
     job->tmodes = tmodes;
 
     job->mut_flags().foreground = !job_node_is_background(job_node);
-    job->mut_flags().job_control = wants_job_control;
 
     // We are about to populate a job. One possible argument to the job is a command substitution
     // which may be interested in the job that's populating it, via '--on-job-exit caller'. Record

src/proc.h

@@ -329,6 +329,9 @@ class job_t {
 
         /// Whether this job was created as part of an event handler.
         bool from_event_handler{};
+
+        /// Whether the job is under job control, i.e. has its own pgrp.
+        bool job_control{};
     };
 
    private:
@@ -443,9 +446,6 @@ class job_t {
         /// Whether the exit status should be negated. This flag can only be set by the not builtin.
         bool negate{false};
 
-        /// Whether the job is under job control, i.e. has its own pgrp.
-        bool job_control{false};
-
         /// This job is disowned, and should be removed from the active jobs list.
         bool disown_requested{false};
 
@@ -460,7 +460,7 @@ class job_t {
     flags_t &mut_flags() { return job_flags; }
 
     /// \return if we want job control.
-    bool wants_job_control() const { return flags().job_control; }
+    bool wants_job_control() const { return properties.job_control; }
 
     /// \return if this job should own the terminal when it runs.
     bool should_claim_terminal() const { return properties.wants_terminal && is_foreground(); }