plotting - Break[] inside ColorFunction

Bug introduced in 8.0 or earlier and persisting through 11.0.1 or later

f[x_?NumericQ]:= (Do[Break[],{i,1,2}];x)
Plot[x,{x,0,1},ColorFunction->(ColorData["Rainbow"][f[#]]&)]

Break::nofwd: No enclosing For, While, or Do found for Break[].

What's going on here? I've tried setting HoldFirst attribute on f and I've also tried using Unevaluated which gives surprising results:

(* Works fine, gives plot colored as expected *)
Plot[x, {x, 0, 1}, 
 ColorFunction -> (Unevaluated[ColorData["Rainbow"][f[#1]]] &)]

(* Gives a black and white plot with error:
   "Unevaluated is not a Graphics primitive or directive" *)

ListContourPlot[IdentityMatrix[3],
  ColorFunction->(Unevaluated[ColorData["Rainbow"][f[#1]]]&)]

Edit This on the other hand works:

Plot[x,{x,0,1},ColorFunction->Function[c,ColorData["Rainbow"][f[c]]]]

Which only difference is that it uses Function[c,ColorData["Rainbow"][f[c]]]] instead of Function[ColorData["Rainbow"][f[Slot[1]]]]]

Comments

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