enable deepcopy on PyObject #757

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.49 :tada:

Comparison is base (bcaba00) 67.03% compared to head (7ef2c93) 67.52%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1039 +/- ## ========================================== + Coverage 67.03% 67.52% +0.49% ========================================== Files 20 20 Lines 2017 2023 +6 ========================================== + Hits 1352 1366 +14 + Misses 665 657 -8 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `67.52% <100.00%> (+0.49%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/JuliaPy/PyCall.jl/pull/1039?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [src/PyCall.jl](https://app.codecov.io/gh/JuliaPy/PyCall.jl/pull/1039?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL1B5Q2FsbC5qbA==) | `67.90% <100.00%> (+2.80%)` | :arrow_up: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/JuliaPy/PyCall.jl/pull/1039/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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[stevengj]

Why not just increment the refcount as proposed in #757?

Or call Python's copy.deepcopy?

[jw3126]

@stevengj Does this PR look good to you?

[jw3126]

@stevengj LGTY?

[jw3126]

Thanks, @stevengj can you tag a release?

[stevengj]

Will do