Always write .landmines

Otherwise, if .landmines exists, and isn't clobbered by the clobber in
compile.py, every build will cause a clobber until .landmines is removed.

Trying to fix http://crbug.com/375459 brought this up. In that case
compile.py wasn't removing .landmines, which is necessary in the case
of a landmines change on two subsequent builds. If .landmines isn't
maintained, then there's nothing to diff against on the second build
and so a clobber won't be correctly triggered.

R=iannucci@chromium.org,kbr@chromium.org
BUG=376359

Review URL: https://codereview.chromium.org/293983017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272341 0039d316-1c4b-4281-b951-d872f2087c98

build/landmines.py

@@ -64,10 +64,7 @@ def set_up_landmines(target, new_landmines):
     if e.errno == errno.EEXIST:
       pass
 
-  if not os.path.exists(landmines_path):
-    with open(landmines_path, 'w') as f:
-      f.writelines(new_landmines)
-  else:
+  if os.path.exists(landmines_path):
     triggered = os.path.join(out_dir, '.landmines_triggered')
     with open(landmines_path, 'r') as f:
       old_landmines = f.readlines()
@@ -82,6 +79,8 @@ def set_up_landmines(target, new_landmines):
     elif os.path.exists(triggered):
       # Remove false triggered landmines.
       os.remove(triggered)
+  with open(landmines_path, 'w') as f:
+    f.writelines(new_landmines)
 
 
 def process_options():