Conversion from ZpFM to its fraction field incorrect

[saraedum]

sage: R = ZqFM(2)
sage: K = R.fraction_field()
sage: K(R.zero())
<blankline>

[saraedum]

David, you know this code much better than I do. I have no idea if this is the best fix for this.

[roed]

Setting branch back....

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New commits:

​87c900c

normalize() FP elements

[roed]

Alright, I've taken a different approach, and added in a test.

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Last 10 new commits:

​cb882fd	Update add_bigoh to account for fixed-mod having a fraction field
​a826978	Fix _tester_add_bigoh
​883e6b5	Fix doctest in local_generic_element.pyx
​52cbd2a	Merge branch 'u/roed/fixed_mod_frac_field' of git://trac.sagemath.org/sage into t/23510/fixed_mod_frac_field
​bc59ffa	Merge branch 't/14825/polynomial_representation_of_a_padic_number' into t/23510/fixed_mod_frac_field
​3292259	Merge branch 'u/saraedum/fixed_mod_frac_field' of git://trac.sagemath.org/sage into t/23510/fixed_mod_frac_field
​dad02c7	Merge branch 'u/saraedum/fixed_mod_frac_field' of git://trac.sagemath.org/sage into t/23510/fixed_mod_frac_field
​189ac2b	Add _test_fraction_field to the coercion tutorial
​98d8256	Merge branch 'u/roed/fixed_mod_frac_field' of git://trac.sagemath.org/sage into develop
​b8de189	Different fix for 23966, add doctest

[roed]

Most of the changes visible are from #23510. This ticket is basically the changes to FP_template.pxi.

[saraedum]

there is one failing doctest from the patchbot which should be unrelated.