JOEL: Did you know that the “gypsy moons” is actually a reference to a popular song title from the 1920s? Mmm hmm. Don’t remember?
I’m sorry to say that Mr. Hodgson is pulling your leg.
While “Gypsy Moon” is meant to evoke “By the Light of the Silvery Moon”, it most certainly is not the same song. “Silvery Moon” is basically a chord progression of: I-IV-V-I-VI-V, so in C:
By the Light [C]
of the silvery moon [F]
I want to spoon [G]
with my baby and
sing [C]
love’s [A7]
tune [G]
(The verses are even less like “Gypsy Moon” so I won’t write them out here.)
Besides being completely different rhythmically and melodically, “Gypsy Moons” chord structure is a little more unusual, with a fairly standard I-vi-iv-V pattern giving way to a walk down from F-major to D-major. If also in C:
I can’t[C] sleep[Am]
Or clean[Dm] my room[G]
Since[C] you and I[Am]
First[Dm] had our swoony swoon[G]
In[F] early June[Fb]
Under the clear[Eb]
Blue gypsy[D]
moon[G]
That walkdown is kind of a tell: It says to the '90s guy “Hey, it’s old-timey!” but I can’t think of a single actual song from the era that does that.
Also, if that’s not good enough, the “Clowns In the Sky” album credits the song to one Michael and Bridget Js Nelsons.
Kind of amusingly, this pops up when you search for “Gypsy Moon” in Brave:
(N.B. Richard Crooks’ “Gipsy Moon” sounds nothing like either song. 
)