cmake does not detect most recent python, it is fixed somehow to 3.4.x

[nashif]

Describe the bug
On a system with multiple versions of python where the binary python actually points to python 3.7, cmake still thinks I want 3.4.x.

This is hardcoded in the boilerplate, when I change:

diff --git a/cmake/app/boilerplate.cmake b/cmake/app/boilerplate.cmake
index d17e3e20e0..907881072f 100644
--- a/cmake/app/boilerplate.cmake
+++ b/cmake/app/boilerplate.cmake
@@ -86,10 +86,7 @@ set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${AUTOCONF_H})
 # that we need to work around until we upgrade to 3.13. Until then we
 # maintain a patched copy in our repo. Bug:
 # https://github.com/zephyrproject-rtos/zephyr/issues/11103
-set(PythonInterp_FIND_VERSION 3.4)
-set(PythonInterp_FIND_VERSION_COUNT 2)
 set(PythonInterp_FIND_VERSION_MAJOR 3)
-set(PythonInterp_FIND_VERSION_MINOR 4)
 set(PythonInterp_FIND_VERSION_EXACT 0)
 set(PythonInterp_FIND_REQUIRED 1)
 include(${ZEPHYR_BASE}/cmake/backports/FindPythonInterp.cmake)

it detect the version I want.

To Reproduce
Install a new version of python, for example in a virtualenv and make it default

Expected behavior
cmake should detect the enabled python configured, not a specific fixed version.

Impact
You might have installed all requirements using one version that cmake will not detect and build will fail.

Additional context
Some CI systems come with lots of python versions installed, this is confusing and doomed to fail if we pick a specific version.

[ulfalizer]

I'm seeing this too, though it's kinda nice in that I get compatibility testing for free. ;)

[SebastianBoe]

To save time, I'd prefer to await the CMake version bump. And then see if the problem persists ...

[nashif]

To save time, I'd prefer to await the CMake version bump. And then see if the problem persists ...

whose time? :-)
I spent like 2 hours trying to figure out why none of the installed python modules our scripts are using are not being found, I guess I am not the only one...

[SebastianBoe]

Was able to reproduce, it seems that when python3.4 is on path it takes priority over any 'python' executable on path.

Will look into a fix.