Simplify construction of run command line

This is an attempt to optimize, but I think it also makes the code less convoluted.

Signed-off-by: Stefan Marr <git@stefan-marr.de>

rebench/model/run_id.py

@@ -240,18 +240,22 @@ def _expand_vars(self, string):
     def cmdline(self):
         if self._cmdline:
             return self._cmdline
+        return self._construct_cmdline()
 
+    def _construct_cmdline(self):
         cmdline = ""
         if self._benchmark.suite.executor.path:
-            cmdline = "%s/" % (self._benchmark.suite.executor.path, )
+            cmdline = self._benchmark.suite.executor.path + "/"
 
-        cmdline += "%s %s" % (self._benchmark.suite.executor.executable,
-                              self._benchmark.suite.executor.args or '')
+        cmdline += self._benchmark.suite.executor.executable + " "
+
+        if self._benchmark.suite.executor.args:
+            cmdline += str(self._benchmark.suite.executor.args) + " "
 
         cmdline += self._benchmark.suite.command
 
-        if self._benchmark.extra_args is not None:
-            cmdline += " %s" % self._benchmark.extra_args
+        if self._benchmark.extra_args:
+            cmdline += str(self._benchmark.extra_args) + " "
 
         cmdline = self._expand_vars(cmdline)