DEBUG: on pexpect failure show 1000 chars buffer

IPython/core/tests/test_debugger.py

@@ -391,6 +391,7 b' def _decorator_skip_setup():'
     child = pexpect.spawn(
         sys.executable, ["-m", "IPython", "--colors=nocolor"], env=env
     )
+    child.str_last_chars = 1000
     child.timeout = 5 * IPYTHON_TESTING_TIMEOUT_SCALE
 
     child.expect("IPython")