Logs should go to stderr

Currently, we log to stdout, which is contrary to UNIX conventions.
Also, it makes it impossible to redirect normal standard output of commands
like cmsRWSHelper to a file.

Closes #1382.

Author: gollux

cms/log.py

@@ -393,16 +393,16 @@ def process(self, msg: str, kwargs: dict):
 
 
 # Install a shell handler.
-shell_handler = StreamHandler(sys.stdout)
+shell_handler = StreamHandler(sys.stderr)
 shell_handler.setLevel(logging.INFO)
-shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stdout)))
+shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stderr)))
 root_logger.addHandler(shell_handler)
 
 
 def set_detailed_logs(detailed: bool):
     """Set or unset the shell logs to detailed."""
     global shell_handler
-    color = has_color_support(sys.stdout)
+    color = has_color_support(sys.stderr)
     formatter = DetailedFormatter(color) \
         if detailed else CustomFormatter(color)
     shell_handler.setFormatter(formatter)

cmsranking/Logger.py

@@ -243,9 +243,9 @@ def format(self, record):
 root_logger.setLevel(logging.DEBUG)
 
 # Define the stream handler to output on stderr.
-shell_handler = StreamHandler(sys.stdout)
+shell_handler = StreamHandler(sys.stderr)
 shell_handler.setLevel(logging.INFO)
-shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stdout)))
+shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stderr)))
 root_logger.addHandler(shell_handler)