paredit considers a seq of #_uneval nodes empty

[lread]

Version
1.1.49

Platform
All

Symptom
The paredit API treats empty sequences as special.
When the zipper is at an empty sequence (because we can't be in an empty sequence) we slurp into that sequence.

The paredit API deems a sequence with #_uneval nodes empty.
I don't think it should.

Reproduction

(-> "[#_uneval] 2"
    z/of-string
    pe/slurp-forward
    z/root-string)

Actual behavior

;; => "[#_uneval 2]"

Expected behavior
Should be a no-op because the sequence is not empty.

;; => "[#_uneval] 2"

To slurp into a non-empty sequence we navigate into it:

(-> "[#_uneval] 2"
    z/of-string
    z/down ;; nav down into non-empty seq
    slurp-forward
    z/root-string)
;; => "[#_uneval 2]"

Diagnosis
Closely related to #336.

Action
Working on it.