Fix: Don't clone Span in _init_tools

[hoxbro]

Fixes #6386

[TheoMathurin]

Thanks for the lightning fast fix!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.49%. Comparing base (3b3f10f) to head (7f731c7).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6387   +/-   ##
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  Coverage   88.49%   88.49%           
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  Files         323      323           
  Lines       68304    68313    +9     
=======================================
+ Hits        60448    60457    +9     
  Misses       7856     7856           

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[philippjfr]

This is not safe. We clone models because a user provided Model can only be used within a single plot. What likely needs to happen is that instead of cloning and replacing the models on a per-plot basis we have to search the entire model graph and replace shared instances all at once.

[hoxbro]

Just to be sure, we still clone the CrosshairTool with tool = type(tool)(**properties). This is to avoid cloning overlay=height in the following. The span in overlay=[height, width] is not cloned.

This is an regression and was only reasonly introduced in #6220.

height = Span(dimension="height")
width = Span(dimension="width")
cht1 = CrosshairTool(overlay=[height, width])
cht2 = CrosshairTool(overlay=height)