Bug#1050797: python-gmpy2 tests need an update due to the fix of the MPFR formatted functions

[Matthias Klose]

Control: tags -1 + patch

these are the two commits needed from the trunk to fix the issue:
https://patches.ubuntu.com/p/python-gmpy2/python-gmpy2_2.1.5-1ubuntu2.patch

for further discussion, please see the upstream report.