Write modified module source to a tempfile so we get correct tracebacks.

Fixes #1306

There's probably some sort of performance penalty, but we don't run all that many monkey files (22 or so), and they take long enough that I suspect its lost in the overhead.

src/greentest/greentest/monkey_test.py

 import sys
 import os
 
+
 kwargs = {}
 
 if sys.argv[1] == '--Event':
@@ -14,7 +15,9 @@ del sys.argv[1]
 
 print('Running with patch_all(%s): %s' % (','.join('%s=%r' % x for x in kwargs.items()), test_filename))
 
-from gevent import monkey; monkey.patch_all(**kwargs)
+from gevent import monkey
+monkey.patch_all(**kwargs)
+
 from greentest.sysinfo import RUNNING_ON_APPVEYOR
 from greentest.sysinfo import PY37
 from greentest.patched_tests_setup import disable_tests_in_source
@@ -39,6 +42,11 @@ if RUNNING_ON_APPVEYOR and PY37:
 __file__ = os.path.join(os.getcwd(), test_filename)
 
 test_name = os.path.splitext(test_filename)[0]
+
+# It's important that the `module_source` be a native
+# string. Passing unicode to `compile` on Python 2 can
+# do bad things: it conflicts with a 'coding:' directive,
+# and it can cause some TypeError with string literals
 if sys.version_info[0] >= 3:
     module_file = open(test_filename, encoding='utf-8')
 else:
@@ -46,5 +54,22 @@ else:
 with module_file:
     module_source = module_file.read()
 module_source = disable_tests_in_source(module_source, test_name)
-module_code = compile(module_source, os.path.abspath(test_filename), 'exec')
-exec(module_code, globals())
+
+# We write the module source to a file so that tracebacks
+# show correctly, since disabling the tests changes line
+# numbers. However, note that __file__ must still point to the
+# real location so that data files can be found.
+# See https://github.com/gevent/gevent/issues/1306
+import tempfile
+temp_handle, temp_path = tempfile.mkstemp(prefix=test_name, suffix='.py', text=True)
+os.write(temp_handle,
+         module_source.encode('utf-8') if not isinstance(module_source, bytes) else module_source)
+os.close(temp_handle)
+try:
+    module_code = compile(module_source,
+                          temp_path,
+                          'exec',
+                          dont_inherit=True)
+    exec(module_code, globals())
+finally:
+    os.remove(temp_path)

src/greentest/greentest/patched_tests_setup.py

@@ -153,6 +153,10 @@ disabled_tests = [
     'test_asyncore.BaseTestAPI.test_handle_expt',
     # sends some OOB data and expect it to be detected as such; gevent.select.select does not support that
 
+    # This one likes to check its own filename, but we rewrite
+    # the file to a temp location during patching.
+    'test_asyncore.HelperFunctionTests.test_compact_traceback',
+
     'test_signal.WakeupSignalTests.test_wakeup_fd_early',
     # expects time.sleep() to return prematurely in case of a signal;
     # gevent.sleep() is better than that and does not get interrupted (unless signal handler raises an error)
@@ -1048,6 +1052,7 @@ _wrapped_tests_by_file = _build_test_structure(wrapped_tests)
 
 
 def disable_tests_in_source(source, filename):
+    # Source and filename are both native strings.
 
     if filename.startswith('./'):
         # turn "./test_socket.py" (used for auto-complete) into "test_socket.py"