Error in fixed field computation

[thofma]

Seems to be random and observerd here here.

Here is the error. CC: @fieker

-> Testing ./NumberTheory/nmbthy.jl took: 2.527 seconds, 140.23 MB
galois_group: Error During Test at /home/runner/work/Oscar.jl/Oscar.jl/test/NumberTheory/galthy.jl:1
  Got exception outside of a @test
  dnw
  Stacktrace:
    [1] error(s::String)
      @ Base ./error.jl:33
    [2] relative_invariant(G::PermGroup, U::PermGroup; Chain::Nothing)
      @ Oscar.GaloisGrp ~/work/Oscar.jl/Oscar.jl/src/NumberTheory/GaloisGrp/GaloisGrp.jl:2262
    [3] relative_invariant
      @ ~/work/Oscar.jl/Oscar.jl/src/NumberTheory/GaloisGrp/GaloisGrp.jl:2203 [inlined]
    [4] fixed_field(GC::Oscar.GaloisGrp.GaloisCtx{Hecke.qAdicRootCtx}, U::PermGroup, extra::Int64)
      @ Oscar.GaloisGrp ~/work/Oscar.jl/Oscar.jl/src/NumberTheory/GaloisGrp/GaloisGrp.jl:2288
    [5] fixed_field(GC::Oscar.GaloisGrp.GaloisCtx{Hecke.qAdicRootCtx}, U::PermGroup)
      @ Oscar.GaloisGrp ~/work/Oscar.jl/Oscar.jl/src/NumberTheory/GaloisGrp/GaloisGrp.jl:2283
    [6] macro expansion
      @ ~/work/Oscar.jl/Oscar.jl/test/NumberTheory/galthy.jl:9 [inlined]
    [7] macro expansion
      @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1151 [inlined]
    [8] top-level scope
      @ ~/work/Oscar.jl/Oscar.jl/test/NumberTheory/galthy.jl:3
    [9] include
      @ ./Base.jl:385 [inlined]
   [10] macro expansion
      @ ./timing.jl:368 [inlined]
   [11] include(str::String)
      @ Main ~/work/Oscar.jl/Oscar.jl/test/runtests.jl:76
   [12] (::Base.var"#834#839"{typeof(include)})(r::Base.RefValue{Any}, args::Tuple{String})
      @ Base ./asyncmap.jl:100
   [13] macro expansion
      @ ./asyncmap.jl:234 [inlined]
   [14] (::Base.var"#850#851"{Base.var"#834#839"{typeof(include)}, Channel{Any}, Nothing})()
      @ Base ./task.jl:417
Test Summary: | Pass  Error  Total
galois_group  |    1      1      2
ERROR: LoadError: LoadError: Some tests did not pass: 1 passed, 0 failed, 1 errored, 0 broken.
in expression starting at /home/runner/work/Oscar.jl/Oscar.jl/test/NumberTheory/galthy.jl:1
in expression starting at /home/runner/work/Oscar.jl/Oscar.jl/test/runtests.jl:152
ERROR: LoadError: Package Oscar errored during testing

[thofma]

Fixed by #2595