bug#36510: confusing mcron logging

[Robert Vollmert]

I have two mcron jobs on my system, certbot renewal and
a handwritten and currently buggy guile job. This is an
excerpt from /var/log/mcron.log:

>>>>>

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Cert not yet due for renewal
Keeping the existing certificate

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Certificate not yet due for renewal; no action taken.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Acquiring or renewing certificate: garp.vllmrt.net
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Cert not yet due for renewal
Keeping the existing certificate

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Certificate not yet due for renewal; no action taken.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Acquiring or renewing certificate: garp.vllmrt.net
Backtrace:
           9 (apply-smob/1 #<catch-closure 5cf300>)
In ice-9/boot-9.scm:
    829:9  8 (catch mcron-error #<procedure 7fe67c318d28 at mcron/s?> ?)
In mcron/scripts/mcron.scm:
     99:7  7 (_)
In mcron/base.scm:
   234:12  6 (_ #<continuation 5ad660>)
In srfi/srfi-1.scm:
    640:9  5 (for-each #<procedure run-job (job)> (#<<job> user: #(?>))
In mcron/base.scm:
   186:10  4 (run-job #<<job> user: #("root" "x" 0 0 "System adminis?>)
In ice-9/eval.scm:
   293:34  3 (_ #(#(#<directory (mcron scripts mcron) 6a9c80>)))
   182:19  2 (proc #(#(#<directory (mcron scripts mcron) 6a9c80>)))
   142:16  1 (compile-top-call _ (7 . get-string-all) ((10 (# . #) ?)))
In unknown file:
           0 (%resolve-variable (7 . get-string-all) #<directory (mc?>)

ERROR: In procedure %resolve-variable:
Unbound variable: get-string-all
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Cert not yet due for renewal
Keeping the existing certificate

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Certificate not yet due for renewal; no action taken.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Acquiring or renewing certificate: garp.vllmrt.net
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Cert not yet due for renewal
Keeping the existing certificate

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Certificate not yet due for renewal; no action taken.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Acquiring or renewing certificate: garp.vllmrt.net

<<<<<

It’s impossible to tell what output is from which job; which jobs succeeded or
didn’t; when they ran.

Suggestions:
- mcron should log the timestamp and a job id of every job when it starts
- mcron should log the timestamp and status and job id of every job when it 
finishes
- job output should be prefixed by some job id