Optimize calls to maybe_signature in canvas

Checklist

• I have checked the issues list for similar or identical enhancement to an existing feature.
• I have checked the pull requests list for existing proposed enhancements.
• I have checked the commit log to find out if the if the same enhancement was already implemented in the master branch.
• I have included all related issues and possible duplicate issues in this issue (If there are none, check this box anyway).

Related Issues and Possible Duplicates

Related Issues

• None

Possible Duplicates

• None

Brief Summary

In canvas.py, there are some calls to maybe_signature which are followed by .clone(): here and here.

These can be optimized by calling maybe_signature with the function param clone set to True, and not calling clone() after the function call.

Design

Architectural Considerations

None

Proposed Behavior

maybe_signature(...).clone() --> maybe_signature(..., clone=True)

Proposed UI/UX

Diagrams

N/A

Alternatives

None