[Issue 20242] BitArray constructor should not modify input data

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20242
Issue 20242 depends on issue 20241, which changed state.

Issue 20241 Summary: BitArray.bitsSet ignores length
https://issues.dlang.org/show_bug.cgi?id=20241

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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