vowpal-wabbit rounding changes in Python 3.12 break unit tests

[Vladimir Petko]

vowpal-wabbit fails to build with due to the rounding changes[1]

See log[2]
e.g.

2>sparse.stderr
--- diff -u --minimal train-sets/ref/sparse.stderr sparse.stderr
--- train-sets/ref/sparse.stderr 2018-07-27 18:21:44.000000000 +0000
+++ sparse.stderr 2024-07-10 18:47:20.902073712 +0000
@@ -9,7 +9,7 @@
 average since example example current current current
 loss last counter weight label predict features
 2.000000 2.000000 1 1.0 known 0:0... 12
-1.000000 0.000000 2 2.0 known 1:-0.0849907... 8
+1.000000 0.000000 2 2.0 known 1:-0.085006... 8

 finished run

[1] https://launchpadlibrarian.net/738855180/buildlog_ubuntu-oracular-amd64.vowpal-wabbit_8.6.1.dfsg1-1build4_BUILDING.txt.gz

[Vladimir Petko (vpa1977)]

The issue is partially caused by rounding (see above) and changes in array printing (appending '...').

Test 144 provides different results and needs to investigated:

RunTests: test 144: stderr OK
--- diff -u --minimal pred-sets/ref/cbe_adf_cover_dr256.predict cbe_adf_cover_dr256.predict
--- pred-sets/ref/cbe_adf_cover_dr256.predict 2018-07-28 06:21:44.000000000 +1200
+++ cbe_adf_cover_dr256.predict 2024-07-12 21:23:55.883132120 +1200
@@ -138,9 +138,9 @@

 1:0.666667,0:0.333333

-1:0.620662,2:0.310331,0:0.0690066
+1:0.465497,2:0.465497,0:0.0690066

-1:0.916082,0:0.0839181
+1:0.666667,0:0.333333

 1:0.465979,2:0.465979,0:0.0680414

@@ -176,11 +176,11 @@

 1:0.469227,2:0.469227,0:0.0615457

-1:0.666667,0:0.333333
+1:0.925047,0:0.0749532

 1:0.469571,2:0.469571,0:0.0608581

-1:0.666667,0:0.333333
+1:0.925875,0:0.0741249

 1:0.469904,2:0.469904,0:0.0601929

RunTests: test 144: FAILED: ref(pred-sets/ref/cbe_adf_cover_dr256.predict) != (cbe_adf_cover_dr256.predict)