fix xaxis settings when printing multiple histograms

slurm-eff-tool.py

@@ -1645,7 +1645,6 @@ def histo_graphs(out_rows: list[OutputRow], args: argparse.Namespace):
     height = 30
     outfileroot = None
     term = args.hterm
-    xax_format = ""
     plotstyle = "set style fill transparent solid 0.35 noborder"
     linestyle = "with steps lw 2"
 
@@ -1677,7 +1676,6 @@ def histo_graphs(out_rows: list[OutputRow], args: argparse.Namespace):
             if metric in ["start"]:
                 edges, counts = histogram_date_table(
                     [getattr(row,"vectors")[metric] for row in out_rows])
-                pass
             else:
                 edges, counts = histogram_metric_table(
                     [getattr(row,"vectors")[metric] for row in out_rows])
@@ -1714,6 +1712,8 @@ def histo_graphs(out_rows: list[OutputRow], args: argparse.Namespace):
         logy = ""
         if args.hlogy:
             logy = "set logscale y\n"
+
+        xax_format = ""
         if metric == "start":
             xax_format = (f'set xdata time\n'
                           f'set timefmt "%s"\n'