Associate a name with database connections

This helps when working out which connection to the database is doing what.

scripts/guix-data-service-process-branch-updated-email.in

@@ -29,6 +29,7 @@
              (guix-data-service branch-updated-emails))
 
 (with-postgresql-connection
+ "process-branch-updated-email"
  (lambda (conn)
    (enqueue-job-for-email
     conn

scripts/guix-data-service-process-jobs.in

@@ -31,6 +31,7 @@
 (setvbuf (current-error-port) 'line)
 
 (with-postgresql-connection
+ "process-jobs"
  (lambda (conn)
    (simple-format #t "Ready to process jobs...\n")
    (process-jobs conn)))

scripts/guix-data-service-query-build-servers.in

@@ -25,4 +25,5 @@
              (squee)
              (guix-data-service builds))
 
-(with-postgresql-connection query-build-servers)
+(with-postgresql-connection "query-build-servers"
+                            query-build-servers)