cli/log: handle SIGPIPE errors

`dvc <command> | head` for example could fail with SIGPIPE and
would print a traceback with BrokenPipeError exception. Now we
redirect do /dev/null in case of error as suggested in Python's
docs: https://docs.python.org/3/library/signal.html\#note-on-sigpipe.

dvc/cli/__init__.py

@@ -189,6 +189,15 @@ def main(argv=None):  # noqa: C901
     except KeyboardInterrupt:
         logger.exception("interrupted by the user")
         ret = 252
+    except BrokenPipeError:
+        import os
+
+        # Python flushes standard streams on exit; redirect remaining output
+        # to devnull to avoid another BrokenPipeError at shutdown
+        # See: https://docs.python.org/3/library/signal.html#note-on-sigpipe
+        devnull = os.open(os.devnull, os.O_WRONLY)
+        os.dup2(devnull, sys.stdout.fileno())
+        ret = 141  # 128 + 13 (SIGPIPE)
     except NotDvcRepoError:
         logger.exception("")
         ret = 253

dvc/logger.py

@@ -163,7 +163,7 @@ class LoggerHandler(logging.StreamHandler):
                 msg, file=self.stream, end=getattr(self, "terminator", "\n")
             )
             self.flush()
-        except RecursionError:
+        except (BrokenPipeError, RecursionError):
             raise
         except Exception:  # noqa, pylint: disable=broad-except
             self.handleError(record)