bug#56772: 29.0.50; regexp-builder window is very tall when temp-buffer-resize-mode is enabled

[Daniel Martín]

Steps to reproduce:

emacs -Q
M-x temp-buffer-resize-mode RET
M-x regexp-builder RET

Actual result:

The regexp-builder window occupies half of the frame's height (much more
than its empty contents would require).

Expected result:

The regexp-builder window takes 4 lines, just as when
temp-buffer-resize-mode is not enabled.

Workaround:

Calling M-x fit-window-to-buffer after M-x regexp-builder resizes the
window successfully.