fix: added missing input files in reason.updated_input in dag.py

Let's consider a 'A' rule that takes 'N' inputs from a 'B' rule with
different wildcards. The input function for the A rule requests output
files from 'B'.

If a first run has already generated the output of 'A' and 'B' and if
the input function of 'A' requests new input files from B not yet
generated, snakemake will neither generate missing 'B' output files
nor regenerate the 'A' output. However the list-input-changes is able
to list correctly the missing files.

The commit allows to generate missing 'B' outputs and regenerate the
'A' output.

snakemake/dag.py

@@ -996,7 +996,9 @@ def update_needrun(job):
                 output_mintime_ = output_mintime.get(job)
                 if output_mintime_:
                     updated_input = [
-                        f for f in job.input if f.exists and f.is_newer(output_mintime_)
+                        f
+                        for f in job.input
+                        if f.exists and f.is_newer(output_mintime_) or not f.exists
                     ]
                     reason.updated_input.update(updated_input)
             if noinitreason and reason: