Revert fdopen mode from 'a' to 'w'

Author: jsiirola

pyomo/common/log.py

@@ -469,7 +469,7 @@ def __enter__(self):
         # #3587), so we will just handle it explicitly ourselves.
         self.local_fd = os.dup(self.fd)
         self.handler.stream = os.fdopen(
-            self.local_fd, mode="a", closefd=False
+            self.local_fd, mode="w", closefd=False
         ).__enter__()
 
     def __exit__(self, et, ev, tb):
@@ -495,7 +495,7 @@ def __enter__(self):
         # #3587), so we will just handle it explicitly ourselves.
         self.local_fd = os.dup(self.fd)
         logging.lastResort = logging.StreamHandler(
-            os.fdopen(self.local_fd, mode="a", closefd=False).__enter__()
+            os.fdopen(self.local_fd, mode="w", closefd=False).__enter__()
         )
 
     def __exit__(self, et, ev, tb):

pyomo/common/tee.py

@@ -169,7 +169,7 @@ def __enter__(self):
 
         if self.synchronize and self.std:
             # Cause Python's stdout to point to our new file
-            self.target_file = os.fdopen(self.fd, 'a', closefd=False)
+            self.target_file = os.fdopen(self.fd, "w", closefd=False)
             setattr(sys, self.std, self.target_file)
 
         return self
@@ -349,7 +349,7 @@ def _enter_impl(self):
                 log_stream = self._enter_context(
                     os.fdopen(
                         self._enter_context(_fd_closer(os.dup(old_fd[1] or 2))),
-                        mode="a",
+                        mode="w",
                         closefd=False,
                     )
                 )
@@ -358,7 +358,7 @@ def _enter_impl(self):
             self._enter_context(LoggingIntercept(log_stream, logger=logger, level=None))
 
             if isinstance(self.output, str):
-                self.output_stream = self._enter_context(open(self.output, 'a'))
+                self.output_stream = self._enter_context(open(self.output, "a"))
             elif self.output is None:
                 self.output_stream = io.StringIO()
             else:
@@ -415,7 +415,7 @@ def _enter_impl(self):
                                     _fd_closer(os.dup(fd_redirect[fd].original_fd)),
                                     prior_to=self.tee,
                                 ),
-                                mode="a",
+                                mode="w",
                                 closefd=False,
                             ),
                             prior_to=self.tee,
@@ -673,7 +673,7 @@ def STDERR(self):
             self._stderr = self.open(buffering=b)
         return self._stderr
 
-    def open(self, mode='a', buffering=-1, encoding=None, newline=None):
+    def open(self, mode="w", buffering=-1, encoding=None, newline=None):
         if encoding is None:
             encoding = self.encoding
         handle = _StreamHandle(mode, buffering, encoding, newline)