invoker: don't show output of captured commands by default

pym/bob/invoker.py

@@ -291,7 +291,11 @@ async def __runCommand(self, args, cwd, stdout=None, stderr=None,
             # If stdout should be captured we use a dedicated buffer. This
             # buffer is then returned to the caller at child exit.
             stdoutRedir = subprocess.PIPE
-            stdoutStreams = [io.BytesIO(), self.__stdoutStream]
+            stdoutStreams = [io.BytesIO()]
+            if self.__trace:
+                # Only show stdout to the user if the command is traced.
+                # Otherwise it is unclear where it came from.
+                stdoutStreams.append(self.__stdoutStream)
         elif stdout == False:
             stdoutRedir = subprocess.DEVNULL
             stdoutStreams = []
@@ -306,7 +310,11 @@ async def __runCommand(self, args, cwd, stdout=None, stderr=None,
             # If stderr should be captured we use a dedicated buffer. This
             # buffer is then returned to the caller at child exit.
             stderrRedir = subprocess.PIPE
-            stderrStreams = [io.BytesIO(), self.__stderrStream]
+            stderrStreams = [io.BytesIO()]
+            if self.__trace:
+                # Only show stderr to the user if the command is traced.
+                # Otherwise it is unclear where it came from.
+                stderrStreams.append(self.__stderrStream)
         elif stderr == False:
             stderrRedir = subprocess.DEVNULL
             stderrStreams = []

pyproject.toml

@@ -1,3 +1,3 @@
 [build-system]
-requires = ["setuptools >= 40.0", "Sphinx"]
+requires = ["setuptools >= 40.0", "setuptools-scm", "Sphinx"]
 build-backend = "setuptools.build_meta"

setup.py

@@ -147,11 +147,6 @@ class build(build_orig):
         'azure' : [ 'azure-storage-blob' ],
     },
 
-    # Installation time dependencies only needed by setup.py
-    setup_requires = [
-        'setuptools_scm',   # automatically get package version
-    ],
-
     # Provide executables
     entry_points = {
         'console_scripts' : [