Description:

makepkg --sign (with myself GPG key, has not add into pacman-key)
pacman -U package.tar.xz
:: Import PGP key [GPG Key, shown as `keyid-format short`], ""? [Y/n] n
pacman coredump

And have random exit output like these:
free(): double free detected in tcache 2
malloc(): unsorted double linked list corrupted
double free or corruption (fasttop)
error: segmentation fault

* Downgrade to pacman 5.1.3 work fine

Additional info:

package version: pacman 5.2.0-2

No partial upgrade
No files corruption

coredump log 1:
Process 274573 (pacman) of user 0 dumped core.

Stack trace of thread 274573:
#0 0x00007fd496796f25 raise (libc.so.6)
#1 0x00007fd496780897 abort (libc.so.6)
#2 0x00007fd4967da258 __libc_message (libc.so.6)
#3 0x00007fd4967e177a malloc_printerr (libc.so.6)
#4 0x00007fd4967e359d _int_free (libc.so.6)
#5 0x00007fd4969ef8f1 alpm_pkg_load (libalpm.so.12)
#6 0x000055c8ab414f57 n/a (pacman)
#7 0x000055c8ab40721a n/a (pacman)
#8 0x00007fd496782153 __libc_start_main (libc.so.6)
#9 0x000055c8ab40844e n/a (pacman)

coredump log 2:
Process 54930 (pacman) of user 0 dumped core.

Stack trace of thread 54930:
#0 0x00007fefda1dff25 raise (libc.so.6)
#1 0x0000562280a460ad n/a (pacman)
#2 0x00007fefda1dffb0 __restore_rt (libc.so.6)
#3 0x00007fefda22ef2e malloc (libc.so.6)
#4 0x00007fefda1dca6f _nl_make_l10nflist.localalias (libc.so.6)
#5 0x00007fefda1dcd83 _nl_make_l10nflist.localalias (libc.so.6)
#6 0x00007fefda1dcd83 _nl_make_l10nflist.localalias (libc.so.6)
#7 0x00007fefda1dcd83 _nl_make_l10nflist.localalias (libc.so.6)
#8 0x00007fefda1daa81 _nl_find_domain (libc.so.6)
#9 0x00007fefda1da1f0 __dcigettext (libc.so.6)
#10 0x00007fefda438986 alpm_pkg_load (libalpm.so.12)
#11 0x0000562280a49f57 n/a (pacman)
#12 0x0000562280a3c21a n/a (pacman)
#13 0x00007fefda1cb153 __libc_start_main (libc.so.6)
#14 0x0000562280a3d44e n/a (pacman)


Steps to reproduce:
makepkg --sign (this key has not add into pacman-key)
pacman -U package