test-fger fails sometimes

[P1K]

test-fger sometimes fails on the current master and up-to-date givaro.
For instance, I get a failure for test-fger -s 1, both on albaron and retourdest (and also on an unknown setup from @ClementPernet).

[d-torrance]

I just saw this on a PPA build of the master branch (amd64, Ubuntu 20.04):

FAIL: test-fger
===============

Checking Modular_implem<double, double, uint64_t> modulo 1840351... PASSED 
Checking Modular_implem<double, double, uint64_t> modulo 49250431... PASSED 
Checking Modular_implem<double, double, uint64_t> modulo 50835119... PASSED 
Checking ......ModularBalanced<double> mod 1.36058e+08... PASSED 
Checking ......ModularBalanced<double> mod 1.83468e+08... PASSED 
Checking ......ModularBalanced<double> mod 9.76825e+07... PASSED 
Checking Modular_implem<float, float, uint32_t> modulo 1259... PASSED 
Checking Modular_implem<float, float, uint32_t> modulo 127... PASSED 
Checking Modular_implem<float, float, uint32_t> modulo 1097... PASSED 
Checking ..............ModularBalanced<float> mod 5351... PASSED 
Checking ...............ModularBalanced<float> mod 127... PASSED 
Checking ..............ModularBalanced<float> mod 1097... PASSED 
Checking Modular_implem<int32_t, uint32_t, uint32_t> modulo 5351... PASSED 
Checking Modular_implem<int32_t, uint32_t, uint32_t> modulo 32887... PASSED 
Checking Modular_implem<int32_t, uint32_t, uint32_t> modulo 33863... PASSED 
Checking ............ModularBalanced<int32_t> mod 5351... PASSED 
Checking ...........ModularBalanced<int32_t> mod 98429... PASSED 
Checking ...........ModularBalanced<int32_t> mod 33863... PASSED 
Checking Modular_implem<int64_t, uint64_t, uint64_t> modulo 2551977193... PASSED 
Checking Modular_implem<int64_t, uint64_t, uint64_t> modulo 1525645397... PASSED 
Checking Modular_implem<int64_t, uint64_t, uint64_t> modulo 185052841... FAIL
a   :185052840
m   :42, n   : 1
incx :1, incy : 1, ldC : 1
Error C[0,0]=89478538 D[0,0]=17218280
Error C[1,0]=94428674 D[1,0]=137280135
Error C[2,0]=59497735 D[2,0]=71559523
Error C[3,0]=51008278 D[3,0]=117920663
Error C[4,0]=18984875 D[4,0]=23856783
Error C[5,0]=34848568 D[5,0]=154018554
Error C[6,0]=116441981 D[6,0]=40276370
Error C[7,0]=146629274 D[7,0]=166959706
Error C[8,0]=19820468 D[8,0]=83536049
Error C[9,0]=9227452 D[9,0]=99986013
Error C[10,0]=125035328 D[10,0]=130660426
Error C[11,0]=178216741 D[11,0]=111724877
Error C[12,0]=2785040 D[12,0]=45578632
Error C[13,0]=118366720 D[13,0]=20268385
Error C[14,0]=37807985 D[14,0]=14184128
Error C[15,0]=174516742 D[15,0]=12532228
Error C[16,0]=15174238 D[16,0]=93602560
Error C[17,0]=151783389 D[17,0]=82352084
Error C[18,0]=11887131 D[18,0]=51642671
Error C[19,0]=73080309 D[19,0]=29711202
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FAILED 
FAIL test-fger (exit status: 1)