install: final: Add some logging.

* gnu/installer/final.scm (umount-cow-store): Add some logging.

gnu/installer/final.scm

@@ -155,6 +155,8 @@ be much appreciated."
         ;; restart it.
         (restart-service 'guix-daemon)
 
+        (syslog "Killing cow users.")
+
         ;; Kill all processes started while the cow-store was active (logins
         ;; on other TTYs for instance).
         (kill-cow-users tmp-dir)
@@ -162,6 +164,7 @@ be much appreciated."
         ;; Try to umount the store overlay. Some process such as udevd
         ;; workers might still be active, so do some retries.
         (let loop ((try 5))
+          (syslog "Umount try ~a~%" (- 5 try))
           (sleep 1)
           (let ((umounted? (false-if-exception (umount tmp-dir))))
             (if (and (not umounted?) (> try 0))