memory leak in hybrid rexgen mode

It seems that I found memory leak within rexgen mode. It happens with salted hashes with high number of salts. --fork does not affect it. Regular rexgen with similar number of candidates seems to be ok.

Amount of memory used goes up and down, but it goes only up at the scale of minutes. It ate 0.5 Gb after 1 minute, 1 Gb after 3 minutes, 2+ Gb after 7 minutes.

rexgen was installed from https://github.com/teeshop/rexgen.git . There was src/patches/john-1.8.0-regex.patch, it was not applied.

Steps to reproduce

$ python -c 'for i in range(300000): print "$dynamic_1${:06d}{:026d}${:032d}".format(i, 0, i)' > t.pw
$ seq 256 > t.lst
$ john --regex='\){2,3}\0[12A\)]{0,4}' --wordlist=t.lst t.pw
[...]

System configuration

$ john --list=build-info
Version: 1.8.0.13-jumbo-1-bleeding-5d6ec13 2018-08-07 22:30:42 +0530
Build: linux-gnu 64-bit x86_64 SSE4.2 AC
SIMD: SSE4.1, interleaving: MD4:3 MD5:3 SHA1:1 SHA256:1 SHA512:1
CPU tests: SSE4.2
[...]
gcc version: 5.1.0
GNU libc version: 2.19 (loaded: 2.19)
Crypto library: OpenSSL
OpenSSL library version: 01000114f
OpenSSL 1.0.1t  3 May 2016
GMP library version: 6.0.0
Regex library version: 2.0	(loaded: 2.0.8)
File locking: fcntl()
fseek(): fseek
ftell(): ftell
fopen(): fopen
memmem(): System's

rexgen$ git log | head -n 3
commit b8cd7b433a1a4c665bc1ca1d33146996d57b33fd
Author: Jan Starke <jan.starke@t-systems.com>
Date:   Mon Mar 5 11:42:53 2018 +0100