tradefed_test: move increment.

Fixes bug. Right now we don't increment at all.

BUG=chromium:798273
TEST=Inspection.

Change-Id: Ic010410df849947ccb321c618b3c76ff96dd2deb
Reviewed-on: https://chromium-review.googlesource.com/849758
Tested-by: Ilja H. Friedel <ihf@chromium.org>
Trybot-Ready: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
(cherry picked from commit fee326e2b0b30910d7c684ddee736829da04549a)
Reviewed-on: https://chromium-review.googlesource.com/849514
(cherry picked from commit f5d976d47b1f84108a2a6a90aa833115b11374da)
Reviewed-on: https://chromium-review.googlesource.com/849515
diff --git a/server/cros/tradefed_test.py b/server/cros/tradefed_test.py
index 094bc44..1e9c687 100644
--- a/server/cros/tradefed_test.py
+++ b/server/cros/tradefed_test.py
@@ -243,11 +243,11 @@
     attempts = 0
     while not filelock.i_am_locking():
         try:
+            attempts += 1
             logging.info('Waiting for cache lock...')
             # We must not use a random integer as the filelock implementations
             # may underflow an integer division.
             filelock.acquire(random.uniform(0.0, pow(2.0, attempts)))
-            attempts += 1
         except (lockfile.AlreadyLocked, lockfile.LockTimeout):
             # Our goal is to wait long enough to be sure something very bad
             # happened to the locking thread. 11 attempts is between 15 and