FATAL: pre-existing shared memory block is still in use

After rails-background-jobs.1 failed to start because of a syntax error:

[...]
16:19:30 rails-background-jobs.1 | exited with code 1
16:19:30 system                  | sending SIGTERM to all processes
16:19:30 redis.1                 | 1565:signal-handler (1461593970) Received SIGTERM scheduling shutdown...
16:19:30 postgresql.1            | LOG:  received smart shutdown request
16:19:30 redis.1                 | 1565:M 25 Apr 16:19:30.956 # User requested shutdown...
16:19:30 rails-web.1             | terminated by SIGTERM
16:19:30 redis.1                 | 1565:M 25 Apr 16:19:30.956 * Removing the unix socket file.
16:19:30 redis.1                 | 1565:M 25 Apr 16:19:30.956 # Redis is now ready to exit, bye bye...
16:19:30 redis.1                 | exited with code 0
16:19:30 postgresql.1            | LOG:  autovacuum launcher shutting down
16:19:30 gitlab-workhorse.1      | terminated by SIGTERM
16:19:35 system                  | sending SIGKILL to all processes

When I ./run again, PosgreSQL fails (log output filtered to postgresql.1):

16:29:18 postgresql.1            | started with pid 1885
16:29:18 postgresql.1            | FATAL:  pre-existing shared memory block (key 5432001, ID 131072) is still in use
16:29:18 postgresql.1            | HINT:  If you're sure there are no old server processes still running, remove the shared memory block or just delete the file "postmaster.pid".
16:29:18 postgresql.1            | exited with code 1