in_place_wipe: not-set arguments are not passed to execv.

For those arguments that are not assigned value, we should keep it as
unspecified when we are using execv to start new process.

BUG=None
TEST=manual

Change-Id: Ib5553d2b01114d6d49622ba27c197737e8393f4e
Reviewed-on: https://chromium-review.googlesource.com/348232
Commit-Ready: Wei-Han Chen <stimim@chromium.org>
Tested-by: Wei-Han Chen <stimim@chromium.org>
Reviewed-by: Chih-Yu Huang <akahuang@chromium.org>
diff --git a/py/gooftool/commands.py b/py/gooftool/commands.py
index 72a3755..2559789 100755
--- a/py/gooftool/commands.py
+++ b/py/gooftool/commands.py
@@ -1003,8 +1003,10 @@
     event_log.Log('wipe_in_place')
     # WipeInPlace(options)
     wipe_args = []
-    wipe_args += ['--cutoff_args', options.cutoff_args]
-    wipe_args += ['--shopfloor_url', options.shopfloor_url]
+    if options.cutoff_args:
+      wipe_args += ['--cutoff_args', options.cutoff_args]
+    if options.shopfloor_url:
+      wipe_args += ['--shopfloor_url', options.shopfloor_url]
     if options.fast:
       wipe_args += ['--fast']
     if options.station_ip: