[FIX] Removed exists=True from MathsOutput

[0nu]

Summary

When setting MathsCommand().inputs.out_file argument, a Trait error is thrown because of the exists=True, although this file is to be created. This PR fixed this by removing the exists=True argument.

Fixes #3384 .

List of changes proposed in this PR (pull-request)

• Removed exists=True from MathsOutput File().

Acknowledgment

• (Mandatory) I acknowledge that this contribution will be available under the Apache 2 license.

[effigies]

I think you're going to need to rerun make check-before-commit. (See https://github.com/nipy/nipype/blob/master/CONTRIBUTING.md#making-a-change)

[codecov]

Codecov Report

Merging #3385 (4362809) into master (6a7837c) will not change coverage.
The diff coverage is 100.00%.

@@ Coverage Diff @@ ## master #3385 +/- ## ======================================= Coverage 65.13% 65.13% ======================================= Files 307 307 Lines 40372 40372 Branches 5336 5336 ======================================= Hits 26297 26297 Misses 13003 13003 Partials 1072 1072 

Flag	Coverage Δ
unittests	64.87% <100.00%> (ø)

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Impacted Files	Coverage Δ
nipype/interfaces/fsl/maths.py	98.25% <100.00%> (ø)

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[effigies]

Ah, nevermind. It seems that exists=True isn't a thing we check for in specs, so no changes would result. Thanks!

[0nu]

Thanks!