Import wiredtiger: a707df12a2503ad39ccdd82a84062faa6a07e082 from branch mongodb-4.4

ref: 7b994a862e..a707df12a2
for: 4.5.1

WT-3726       Add documentation specifying build pre-requisites
WT-5260       Restore assert that trees being discarded are not marked dirty
WT-5544       Fix cache stuck during salvage
WT-5573       Re-enable unit test test_util01.test_dump_process_timestamp_old
WT-5614       Coverity: Redundant NULL check
WT-5623       Support reading modify type updates in the history store for non-timestamp tables
WT-5661       Make WiredTiger utilities self documenting
WT-5676       Prepare support with durable history: add workgen stress tests
WT-5697       Dropping or renaming tables returns EBUSY in incremental backup test
WT-5728       Coverity analysis defect 114081: PW.SET_BUT_NOT_USED
WT-5749       Only pass a non-NULL WT_ITEM value when allocating a WT_UPDATE with associated data
WT-5764       Fix and reenable test_compact02
WT-5790       Disable test_wt2246_col_append
WT-5883       Add upgrade/downgrade testing to WiredTiger standalone tests
WT-5911       History store verification re-architecture
WT-5912       Change page deletion assert condition in __split_insert()
WT-5954       Turn off column store test and lower isolation levels in test_random_abort
WT-6010       Workgen changes - Add session config at Thread level
WT-6031       Remove legacy WT_PAGE_MODIFY.last_stable_timestamp
WT-6033       Clean up unused unittest imports
WT-6044       Coverity: Variable set but never used
WT-6045       Minor cleanup for test_random_abort
WT-6047       Coverity: Redundant NULL check
WT-6049       Fix eviction evicting uncommitted changes
WT-6050       Close the metadata cursor after bulk loading
WT-6053       fixed-width column-store macro can step past the end of allocated memory
WT-6073       Don't append the tombstone to the update chain if it is already there
WT-6078       Temporarily disable hs verify to unblock wiredtiger drop
WT-6081       Switch wtperf defaults to mirror MongoDB defaults

1 files changed, 1 insertions, 1 deletions

diff --git a/src/third_party/wiredtiger/test/suite/test_txn09.py b/src/third_party/wiredtiger/test/suite/test_txn09.py
index a6ca3a64082..98c7dbd9c48 100644
--- a/src/third_party/wiredtiger/test/suite/test_txn09.py
+++ b/src/third_party/wiredtiger/test/suite/test_txn09.py
@@ -30,7 +30,7 @@
 #   Transactions: recovery toggling logging
 #
 
-import fnmatch, os, shutil, time, unittest
+import fnmatch, os, shutil, time
 from suite_subprocess import suite_subprocess
 from wtscenario import make_scenarios
 import wttest