String_copier::well_formed_copy inefficient for appending 0 bytes

#0  0x00000000041ce6b3 in my_scan_8bit (cs=0x7988400 <my_charset_utf8mb3_bin>, str=0x60dd <error: Cannot access memory at address 0x60dd>, 

    end=0x7b96d7415f38 "", sq=2) at /home/dan/repos/mariadb-server-11.8/strings/ctype-simple.c:1182

#1  0x0000000000d9ca10 in charset_info_st::scan (this=0x7988400 <my_charset_utf8mb3_bin>, b=0x60dd <error: Cannot access memory at address 0x60dd>, 

    e=0x7b96d7415f38 "", seq=2) at /home/dan/repos/mariadb-server-11.8/include/m_ctype.h:1037

#2  0x0000000001c1e345 in test_if_important_data (cs=0x7988400 <my_charset_utf8mb3_bin>, str=0x60dd <error: Cannot access memory at address 0x60dd>, 

    strend=0x7b96d7415f38 "") at /home/dan/repos/mariadb-server-11.8/sql/field.cc:1028

#3  0x0000000001c6b939 in Field_longstr::report_if_important_data (this=0x7e36d74e62f8, pstr=0x60dd <error: Cannot access memory at address 0x60dd>, 

    end=0x7b96d7415f38 "", count_spaces=false) at /home/dan/repos/mariadb-server-11.8/sql/field.cc:7451

#4  0x0000000001cb84ec in Field_longstr::check_conversion_status (this=0x7e36d74e62f8, copier=0x7b66d60e5d20, end=0x7b96d7415f38 "", 

    cs=0x7988400 <my_charset_utf8mb3_bin>, count_spaces=false) at /home/dan/repos/mariadb-server-11.8/sql/field.h:2296

#5  0x0000000001ca91ef in Field_longstr::well_formed_copy_with_check (this=0x7e36d74e62f8, to=0x7d66d73e24d5 "", to_length=765, 

    from_cs=0x7988400 <my_charset_utf8mb3_bin>, from=0x7b96d7415f38 "", from_length=0, nchars=255, count_spaces=false, copy_length=0x7b66d5fc0de0)

    at /home/dan/repos/mariadb-server-11.8/sql/field.h:2311

#6  0x0000000001c6c668 in Field_string::store (this=0x7e36d74e62f8, from=0x7b96d7415f38 "", length=0, cs=0x7988400 <my_charset_utf8mb3_bin>)

    at /home/dan/repos/mariadb-server-11.8/sql/field.cc:7532

#7  0x0000000001da3207 in Item::save_str_value_in_field (this=0x7e36d74d7ef8, field=0x7e36d74e62f8, result=0x7e36d74d7f20)

    at /home/dan/repos/mariadb-server-11.8/sql/item.cc:426

#8  0x0000000001dfefc4 in Item_string::save_in_field (this=0x7e36d74d7ef8, field=0x7e36d74e62f8, no_conversions=true)

    at /home/dan/repos/mariadb-server-11.8/sql/item.cc:7327

#9  0x0000000001c1b200 in Field::make_empty_rec_store_default_value (this=0x7e36d74e62f8, thd=0x7e26d7500218, item=0x7e36d74d7ef8)

    at /home/dan/repos/mariadb-server-11.8/sql/field.cc:1584

#10 0x000000000139586b in make_empty_rec_store_default (thd=0x7e26d7500218, regfield=0x7e36d74e62f8, field=0x7e36d74d6438)

    at /home/dan/repos/mariadb-server-11.8/sql/unireg.cc:1171

#11 0x00000000013912dc in make_empty_rec (thd=0x7e26d7500218, buff=0x7d66d73e24d4 "\001", table_options=8, 

    create_fields=@0x7b66d63f7bf0: {<base_list> = {<Sql_alloc> = {<No data fields>}, first = 0x7e36d74d60a0, last = 0x7e36d74d6210, elements = 24}, <No data fields>}, reclength=1363, data_offset=1) at /home/dan/repos/mariadb-server-11.8/sql/unireg.cc:1246

#12 0x0000000001386775 in build_frm_image (thd=0x7e26d7500218, table=@0x7b66d63f7b80: {str = 0x7e36d74d1428 "db", length = 2}, create_info=0x7b66d63f7870, 

    create_fields=@0x7b66d63f7bf0: {<base_list> = {<Sql_alloc> = {<No data fields>}, first = 0x7e36d74d60a0, last = 0x7e36d74d6210, elements = 24}, <No data fields>}, keys=2, key_info=0x7e36d74e60c0, db_file=0x7e36d74e5868) at /home/dan/repos/mariadb-server-11.8/sql/unireg.cc:576

#13 0x000000000110e07b in mysql_create_frm_image (thd=0x7e26d7500218, create_info=0x7b66d63f7870, alter_info=0x7b66d63f7b70, create_table_mode=0, 

    key_info=0x7b66d6357c20, key_count=0x7b66d6357c40, frm=0x7b66d6357ee0) at /home/dan/repos/mariadb-server-11.8/sql/sql_table.cc:4590

#14 0x00000000011221ce in create_table_impl (thd=0x7e26d7500218, ddl_log_state_create=0x7b66d6222220, ddl_log_state_rm=0x7b66d6222260, 

    orig_db=@0x7e36d74d14a8: {<Lex_ident_fs> = {<Lex_ident<Compare_table_names>> = {<Lex_cstring> = {<st_mysql_const_lex_string> = {str = 0x7e36d74d1468 "mysql", length = 5}, <No data fields>}, <No data fields>}, <No data fields>}, <No data fields>}, 

    orig_table_name=@0x7e36d74d14b8: {<Lex_ident_fs> = {<Lex_ident<Compare_table_names>> = {<Lex_cstring> = {<st_mysql_const_lex_string> = {str = 0x7e36d74d1428 "db", length = 2}, <No data fields>}, <No data fields>}, <No data fields>}, <No data fields>}, 

    db=@0x7e36d74d14a8: {str = 0x7e36d74d1468 "mysql", length = 5}, table_name=@0x7e36d74d14b8: {str = 0x7e36d74d1428 "db", length = 2}, 

    path=@0x7b66d6357f00: {str = 0x7b66d6357c50 "./mysql/db", length = 10}, options={m_options = DDL_options_st::OPT_IF_NOT_EXISTS}, 

    create_info=0x7b66d63f7870, alter_info=0x7b66d63f7b70, create_table_mode=0, is_trans=0x7b66d62222a0, key_info=0x7b66d6357c20, key_count=0x7b66d6357c40,