Configure Combinations fails on ex_file_system error

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   WiredTiger 2.8.1: examples/c/test-suite.log

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# TOTAL: 22

# PASS:  21

# SKIP:  0

# XFAIL: 0

# FAIL:  1

# XPASS: 0

# ERROR: 0

.. contents:: :depth: 2

FAIL: ex_file_system

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[1465561506:777383][34850:0x7f0088037740], file:WiredTigerLAS.wt, connection: WT_HOME.Yt2Y/WiredTigerLAS.wt: handle-read: failed to read 4096 bytes at offset 0: Invalid argument

Error connecting to .: Invalid argument

Custom file system configuration

	key config_string="demo-file-system"

	key config_value=37

Custom file system

	11 unique file opens

	17 opened

	17 closed

FAIL ex_file_system (exit status: 1)