[SPARK-15975] Fix improper Popen retcode code handling in dev/run-tests

In the `dev/run-tests.py` script we check a `Popen.retcode` for success using `retcode > 0`, but this is subtlety wrong because Popen's return code will be negative if the child process was terminated by a signal: https://docs.python.org/2/library/subprocess.html#subprocess.Popen.returncode

In order to properly handle signals, we should change this to check `retcode != 0` instead.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #13692 from JoshRosen/dev-run-tests-return-code-handling.

dev/run-tests.py

@@ -294,7 +294,7 @@ def exec_sbt(sbt_args=()):
             print(line, end='')
     retcode = sbt_proc.wait()
 
-    if retcode > 0:
+    if retcode != 0:
         exit_from_command_with_retcode(sbt_cmd, retcode)
 
 

dev/sparktestsupport/shellutils.py

@@ -53,7 +53,10 @@ else:
 
 
 def exit_from_command_with_retcode(cmd, retcode):
-    print("[error] running", ' '.join(cmd), "; received return code", retcode)
+    if retcode < 0:
+        print("[error] running", ' '.join(cmd), "; process was terminated by signal", -retcode)
+    else:
+        print("[error] running", ' '.join(cmd), "; received return code", retcode)
     sys.exit(int(os.environ.get("CURRENT_BLOCK", 255)))