Multi-phase job has passing job(s) which register (intermittently) as failure due to UnauthorizedAccessException

Selected test(s): LocalTest.SearchTests+ForRent.FRC_BrowseFeatProps_PhoneNumberVerification
..
Tests run: 2, Errors: 0, Failures: 0, Inconclusive: 0, Time: 27.1172522 seconds
Not run: 0, Invalid: 0, Ignored: 0, Skipped: 0

Unhandled Exception:
System.UnauthorizedAccessException: Access to the path 'c:\jenkins\workspace\Browse Featured Property Phone Number Verification\TestResult.xml' is denied.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize)
at System.IO.StreamWriter..ctor(String path)
at NUnit.ConsoleRunner.ConsoleUi.Execute(ConsoleOptions options)
at NUnit.ConsoleRunner.Runner.Main(String[] args)

c:\jenkins\workspace\Browse Featured Property Phone Number Verification>exit -100
Build step 'Execute Windows batch command' marked build as failure
Recording NUnit tests results
Finished: FAILURE