Looking at a few other sanity pre-cq requests recently:

mysql> select *  from buildRequestTable where request_reason='sanity-pre-cq' order by id desc limit 5;
+----+----------+----------------------------+--------------------+------------------------+----------------+---------------------+
| id | build_id | request_build_config       | request_build_args | request_buildbucket_id | request_reason | timestamp           |
+----+----------+----------------------------+--------------------+------------------------+----------------+---------------------+
| 49 |  1777490 | celes-no-vmtest-pre-cq     | NULL               | 8970524397818500992    | sanity-pre-cq  | 2017-08-22 21:44:59 |
| 48 |  1777490 | whirlwind-no-vmtest-pre-cq | NULL               | 8970524717338090080    | sanity-pre-cq  | 2017-08-22 21:39:55 |
| 47 |  1777490 | cyan-no-vmtest-pre-cq      | NULL               | 8970524717631212464    | sanity-pre-cq  | 2017-08-22 21:39:55 |
| 46 |  1777490 | binhost-pre-cq             | NULL               | 8970524717942033344    | sanity-pre-cq  | 2017-08-22 21:39:55 |
| 45 |  1777490 | lumpy-no-vmtest-pre-cq     | NULL               | 8970524718359926240    | sanity-pre-cq  | 2017-08-22 21:39:54 |
+----+----------+----------------------------+--------------------+------------------------+----------------+---------------------+

https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/no_vmtest_pre_cq/builds/102455
https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/no_vmtest_pre_cq/builds/102518
https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/no_vmtest_pre_cq/builds/102456
https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/no_vmtest_pre_cq/builds/102457

The cleanup issue is not widespread.
Next up, check the buildslave involved.

That buildslave is also doing fine: https://uberchromegw.corp.google.com/i/chromiumos.tryserver/buildslaves/cros-standard104-c2

Spot checked recent binhost-pre-cq, and some of them have passed, and I don't see a pattern in the failures. False alarm:
mysql> select build_config, status, buildbucket_id from buildTable where build_config = 'binhost-pre-cq' and status != 'inflight' order by id desc limit 5 \G
*************************** 1. row ***************************
  build_config: binhost-pre-cq
        status: fail
buildbucket_id: 8970522757988279280
*************************** 2. row ***************************
  build_config: binhost-pre-cq
        status: pass
buildbucket_id: 8970523696617191488
*************************** 3. row ***************************
  build_config: binhost-pre-cq
        status: pass
buildbucket_id: 8970523703089768016
*************************** 4. row ***************************
  build_config: binhost-pre-cq
        status: pass
buildbucket_id: 8970524347507233664
*************************** 5. row ***************************
  build_config: binhost-pre-cq
        status: fail
buildbucket_id: 8970524509523248288
5 rows in set (0.13 sec)