support/testing: test_python.py: disable interpreter colors

Python 3.14 (not yet in Buildroot) introduced colors, enabled by
default, when the output is a terminal. This behavior can make the
pexpect pattern matching more difficult in some cases. See:
https://docs.python.org/3.14/using/cmdline.html#controlling-color

This commit globally disables the Python interpreter colors in the base
runtime Python test, by setting the NO_COLOR=1 environment variable.

Signed-off-by: Julien Olivain <ju.o@free.fr>
(cherry picked from commit 3a6e2b4a03)
Signed-off-by: Thomas Perale <thomas.perale@mind.be>

support/testing/tests/package/test_python.py

@@ -17,6 +17,9 @@ class TestPythonBase(infra.basetest.BRTest):
                            kernel="builtin",
                            options=["-initrd", cpio_file])
         self.emulator.login()
+        # Disable Python colors for all Python tests, to make pexpect
+        # pattern matching easier.
+        self.assertRunOk("export NO_COLOR=1")
 
     def version_test(self, version, timeout=-1):
         cmd = self.interpreter + " --version 2>&1 | grep '^{}'".format(version)