Inconsistent behavior when ^ operates on an equation

First, ?mequalp is an internal function--using it at user-level is bad form. Second, my code did the mequalp check on the
wrong argument. Let's try:

(%i1) mequalp(x) := not mapatom(x) and op(x)="="$

(%i2) distribute_power(e) := subst("^" = lambda([a,b], if mequalp(b) then map(lambda([s], a^s), b) else funmake("^",[a,b])), e)$

(%i3) distribute_power([exp(a=b), 2^(a=b), x^2 + 1 = 42]);
(%o3) [%e^a=%e^b,2^a=2^b,x^2+1=42]

--Barton

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Maybe a simple utility would be a workaround:

(%i33) distribute_power(e) := subst("^" = lambda([a,b], if ?mequalp(a) then map(lambda([s], s^b), a) else funmake("^",[a,b])), e)$