The original code would return standard "Please come back later" page when there
are only fetch errors on a newly setup declarative project. The problem is that
there are two types of errors: standard errors and fetch errors. Each is
acompanied by a corresponding field for time of occurence. Standard errors use
'errortime', while fetch errors have 'lastchecktime' set to the time of the
error. Unfortunately, jobset.tt file was only using 'errortime' for displaying
the time. This would result in the following errors in logs:

    Couldn't render template "date error - bad time/date string:  expects 'h:m:s d:m:y'  got: ''

This change includes using 'lastchecktime' when rendering the error times.