Coral device fails with the below error message.

Test details - https://sponge.corp.google.com/target?tab=Output+Files&sortBy=STATUS&show=ALL&id=cbe99991-74b0-4c87-9c42-e6d362192b32&target=coral-release/R67-10575.22.0/bvt-inline/build_RootFilesystemSize&searchFor=user:chromeos-test+build:coral-release/R67-10575.22.0+suite:bvt-inline+build_RootFilesystemSize


Test failure link - https://sponge.corp.googleusercontent.com/file?invocationId=cbe99991-74b0-4c87-9c42-e6d362192b32&targetResultIndex=0&largeText=logs%2Fdebug%2Fclient.0.INFO&filename=client.0.INFO&contentType=text%2Fplain%3B%20charset%3Dutf-8&format=ansi&setTZID=America%2FLos_Angeles
TestFail: 8495104 bytes free is less than the 15728640 required.

Logs snapshot:
04/30 11:41:03.390 INFO |               job:0200| Writing results to /usr/local/autotest/results/default
04/30 11:41:03.726 INFO |               job:0232| START	----	----	timestamp=1525113663	localtime=Apr 30 11:41:03	
04/30 11:41:03.774 INFO |          packages:0190| Fetching packages.checksum from http://100.115.219.132:8082/static/coral-release/R67-10575.22.0/autotest/packages to /usr/local/autotest/packages.checksum
04/30 11:41:03.813 INFO |          packages:0207| Successfully fetched packages.checksum from http://100.115.219.132:8082/static/coral-release/R67-10575.22.0/autotest/packages/packages.checksum
04/30 11:41:03.903 INFO |               job:0232| 	START	build_RootFilesystemSize	build_RootFilesystemSize	timestamp=1525113663	localtime=Apr 30 11:41:03	
04/30 11:41:03.998 INFO |          packages:0190| Fetching test-build_RootFilesystemSize.tar.bz2 from http://100.115.219.132:8082/static/coral-release/R67-10575.22.0/autotest/packages to /usr/local/autotest/packages/test-build_RootFilesystemSize.tar.bz2
04/30 11:41:04.057 INFO |          packages:0207| Successfully fetched test-build_RootFilesystemSize.tar.bz2 from http://100.115.219.132:8082/static/coral-release/R67-10575.22.0/autotest/packages/test-build_RootFilesystemSize.tar.bz2
04/30 11:41:04.233 INFO |              test:0907| Starting before_hook for build_RootFilesystemSize
04/30 11:41:04.237 INFO |              test:0911| before_hook completed
04/30 11:41:04.354 INFO |      base_sysinfo:0395| ChromeOS BOARD = coral_1.1GHz_4GB
04/30 11:41:04.458 WARNI|              test:0637| The test failed with the following exception
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 631, in _exec
    _call_test_function(self.execute, *p_args, **p_dargs)
  File "/usr/local/autotest/common_lib/test.py", line 831, in _call_test_function
    return func(*args, **dargs)
  File "/usr/local/autotest/common_lib/test.py", line 495, in execute
    dargs)
  File "/usr/local/autotest/common_lib/test.py", line 362, in _call_run_once_with_retry
    postprocess_profiled_run, args, dargs)
  File "/usr/local/autotest/common_lib/test.py", line 400, in _call_run_once
    self.run_once(*args, **dargs)
  File "/usr/local/autotest/tests/build_RootFilesystemSize/build_RootFilesystemSize.py", line 59, in run_once
    (free, required_free_space))
TestFail: 8495104 bytes free is less than the 15728640 required.
04/30 11:41:04.480 INFO |              test:0924| Starting after_hook for build_RootFilesystemSize
04/30 11:41:05.093 INFO |              test:0928| after_hook completed
04/30 11:41:05.095 ERROR|          parallel:0026| child process failed
04/30 11:41:05.159 INFO |               job:0232| 		FAIL	build_RootFilesystemSize	build_RootFilesystemSize	timestamp=1525113665	localtime=Apr 30 11:41:05	8495104 bytes free is less than the 15728640 required.
04/30 11:41:05.170 INFO |               job:0232| 	END FAIL	build_RootFilesystemSize	build_RootFilesystemSize	timestamp=1525113665	localtime=Apr 30 11:41:05	
04/30 11:41:12.265 INFO |               job:0232| END GOOD	----	----	timestamp=1525113672	localtime=Apr 30 11:41:12