[release-1.18] fix: return better error when using pack+python

[knative-prow-robot]

This is an automated cherry-pick of #2904

[matejvasek]

Probably best we can do for 1.18 is better error message. Pack simple won't work with python there.

[matejvasek]

Also many test will probably fail because the test code is not updated for the ever changing outer word.

[knative-prow[bot]]

@knative-prow-robot: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
unit-tests_func_release-1.18	f801c1303e1513be6a5d742147a972358844d367	link	true	/test unit-tests

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[codecov[bot]]

Codecov Report

:x: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 48.66%. Comparing base (c1160e1) to head (f801c13).

Files with missing lines	Patch %	Lines
pkg/builders/buildpacks/builder.go	0.00%	2 Missing and 1 partial :warning:

Additional details and impacted files

@@               Coverage Diff                @@
##           release-1.18    #3090      +/-   ##
================================================
+ Coverage         48.42%   48.66%   +0.23%     
================================================
  Files               129      131       +2     
  Lines             15787    15799      +12     
================================================
+ Hits               7645     7688      +43     
+ Misses             7455     7425      -30     
+ Partials            687      686       -1     

Flag	Coverage Δ
unit-tests	48.66% <0.00%> (?)

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[gauron99]

yeah that looks reasonable to me

/lgtm /approve

[knative-prow[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gauron99, knative-prow-robot

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[gauron99]

/hold for @lkingland input

[gauron99]

/unhold

[lkingland]

/hold for @lkingland input

Seems reasonable.

/retest

[lkingland]

/retest

[gauron99]

the tests will probably fail because we dont have the new implementations yet. I think the idea was to just get the message into the 1.18 for better error message instead of rebasing and working through conflicts.

You will have to override all those to get the merge in. run /override ? the bot will tell you what to overwrite explicitly (copy strings with ")