One of our automated tests failed running test_txn06 due to the following content being present in stdout:

[1514856535:149690][21024:0x3fffa7eff1d0], test_txn06.test_txn06.test_long_running, eviction-server: old snapshot 122071 pinned in session 17 [WT_CURSOR.insert] with snap_min 122071

The error message is exactly what this test case was looking for:
https://github.com/wiredtiger/wiredtiger/commit/484c6ccd26ef2c5e5893cac00eaa5b627d4f4839

It appears as though the transaction ID isn't being updated in a timely fashion.