Upgrade to pynac-0.7.15

[rwst]

In 0.7.15:

• fix mpz conversion (Doctest: bug numerical_approx(2^(450232897/4888643760)) #24418)
• fix infinity.info(), function.info(), power.info(negative)
• fix symbol.real/imag_part()
• fix bug showing with nonnumeric rationals
• fix Python import from sage.rings
• rational symbol domain (Rational assumption / variable domain / query #24368)
• implement constant.is_nonzero() (Doctest: Expression.is_positive/negative fixed #18630)
• fully implement info(even) (Even assumption / variable domain / query #24351)
• fully implement info(nonzero)
• fully implement info(rational)

https://github.com/pynac/pynac/releases/download/pynac-0.7.15/pynac-0.7.15.tar.bz2

CC: @kiwifb

Component: packages: standard

Author: Ralf Stephan

Branch/Commit: d085587

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/24497

[rwst]

Description changed:

--- 
+++ 
@@ -10,3 +10,4 @@
 * fully implement `info(nonzero)`
 * fully implement `info(rational)`
 
+https://github.com/pynac/pynac/releases/download/pynac-0.7.15/pynac-0.7.15.tar.bz2

[rwst]

Branch: u/rws/upgrade_to_pynac_0_7_15

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Commit: 880ebf3

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New commits:

907aff6	24497: pkg version/chksum
880ebf3	24497: doctest fixes

[rwst]

Author: Ralf Stephan

[videlec]

comment:5

All tests pass on quasar.

[tscrim]

comment:6

The only thing I'm not sure about is the change in modular/modform_hecketriangle/graded_ring_element.py. Can you explain the rationale?

[rwst]

comment:7

The former result changes quite a bit, I think because small changes are enlarged by substitution into a polynomial. I tried to preserve the assumed spirit of the test, i.e. a nonzero real part of the result, but to make it more robust. Of course I may be wrong with my assumptions.

[jdemeyer]

comment:8

Passes tests on sardonis (ppc64le) too.

[jdemeyer]

Changed branch from u/rws/upgrade_to_pynac_0_7_15 to u/jdemeyer/upgrade_to_pynac_0_7_15