lib.log.log(): Use .join() to build argument string

The argument string builder in log() previously iterated with
enumerate and checked per-iteration whether to prepend a space.
Replace the loop with ' '.join(str(a) for a in args), which is a
single C-level operation.

Move the leading-space logic after the only_printable block so the
regex transformations see the raw joined content.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/log.py

@@ -229,13 +229,14 @@ def log(  # export
 
     margs = ''
     if len(args):
-        for i, a in enumerate(args):
-            margs += (' ' if (i or (msg and not msg.endswith(' '))) else '') + str(a)
+        margs = ' '.join(str(a) for a in args)
         if only_printable:
             margs = _special_char_regex.sub(
                 lambda mo: _special_chars[mo.string[mo.start():mo.end()]], margs
             )
             margs = re.sub('[\x01-\x1f]', '.', margs)
+    if msg and not msg.endswith(' '):
+        margs = ' ' + margs
 
     for file in _log_file_streams:
         print(msg + _clean_log_prefix + margs, file = file)