Add test for binary log file issue

This replicates snakemake#2826

Unfortunately this test seems to currently crush the pytest test execution

tests/test_issue2826_failed_binary_logs/Snakefile

@@ -0,0 +1,12 @@
+rule:
+    log:
+        'log.bin'
+    run:
+        import pickle
+        with open(log[0], 'wb') as f:
+            # Write anything binary to the file
+            # that cannot be interpreted as unicode
+            # dumping the log object was an easy way to do this 
+            pickle.dump(log, f)
+        # make this test fail
+        a

tests/tests.py

@@ -616,6 +616,15 @@ def test_dup_out_patterns():
     run(dpath("test_dup_out_patterns"), shouldfail=True)
 
 
+def test_issue2826_failed_binary_logs():
+    """Show how a binary log file crushes `show_failed_logs`
+
+    The log file is a binary file. `show_failed_logs` is
+    the default option for `run` and should not fail despite the
+    binary log file.
+    """
+    run(dpath("test_issue2826_failed_binary_logs"), shouldfail=True)
+
 # TODO reactivate once generic cluster executor is properly released
 # @skip_on_windows
 # def test_restartable_job_cmd_exit_1_no_restart():