python: support no_header in OutputFormat filter()

Problem: In the future the header may be needed in calculations
within the OutputFormat filter() function.  There is no way to
inform the filter() function that the header should not be considered
(for example, if the header fill not be output).

Add a no_header flag to the filter() function in OutputFormat().  This
parameter currently does nothing.

Update all callers as needed.

Author: chu11

src/bindings/python/flux/util.py

@@ -948,7 +948,7 @@ def format(self, obj):
             raise KeyError(f"Invalid format field {exc} for {typestr}")
         return retval
 
-    def filter(self, items):
+    def filter(self, items, no_header=False):
         """
         Check for format fields that are prefixed with `?:` (e.g. "?:{name}"),
         and filter them out of the current format string if they result in an
@@ -963,6 +963,7 @@ def filter(self, items):
 
         Args:
             items (iterable): list of items to consider for output
+            no_header (boolean): do not use header in calculations (default: False)
         """
 
         #  Build a list of all format strings that have one of the width
@@ -1132,7 +1133,7 @@ def print_items(self, items, no_header=False, pre=None, post=None):
             post (callable): Function to call after printing each item
         """
         #  Preprocess original format by processing with filter():
-        newfmt = self.filter(items)
+        newfmt = self.filter(items, no_header=no_header)
         #  Get the current class for creating a new formatter instance:
         cls = self.__class__
         #  Create new instance of the current class from filtered format:

src/cmd/flux-jobs.py

@@ -545,7 +545,7 @@ def main():
         formatter.set_sort_keys(args.sort)
 
     (jobs, truncated) = fetch_jobs(args, formatter.fields)
-    sformatter = JobInfoFormat(formatter.filter(jobs))
+    sformatter = JobInfoFormat(formatter.filter(jobs, no_header=args.no_header))
 
     if not args.no_header:
         print(sformatter.header())

src/cmd/flux-pgrep.py

@@ -274,7 +274,7 @@ def main():
     if PROGRAM == "flux-pkill":
         pkill(fh, args, jobs)
 
-    sformatter = JobInfoFormat(formatter.filter(jobs))
+    sformatter = JobInfoFormat(formatter.filter(jobs, args.no_header))
 
     # "default" can be overridden by environment variable, so check if
     # it's different than the builtin default