Here is the full backtrace also:

Thread 7 "PK-Backend" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff2431700 (LWP 7552)]
strlen () at ../sysdeps/x86_64/strlen.S:106
106	../sysdeps/x86_64/strlen.S: No such file or directory.
(gdb) bt full
#0  strlen () at ../sysdeps/x86_64/strlen.S:106
No locals.
#1  0x00007ffff65efba9 in __add_to_environ (
    name=name@entry=0x7ffff1a289ef "http_proxy", value=value@entry=0x0, 
    combined=combined@entry=0x0, replace=replace@entry=1) at setenv.c:131
        ep = <optimized out>
        size = <optimized out>
        namelen = 10
        vallen = <optimized out>
#2  0x00007ffff65efcca in __setenv (
    name=name@entry=0x7ffff1a289ef "http_proxy", value=value@entry=0x0, 
    replace=replace@entry=1) at setenv.c:259
        replace = 1
        value = 0x0
        name = 0x7ffff1a289ef "http_proxy"
#3  0x00007ffff1a175cf in AptIntf::init (this=this@entry=0x555555837ed0)
    at apt-intf.cpp:94
        locale = <optimized out>
        http_proxy = 0x0
        ftp_proxy = <optimized out>
        withLock = <optimized out>
        AllowBroken = <optimized out>
        role = <optimized out>
---Type <return> to continue, or q <return> to quit---
        simulate = <optimized out>
        timeout = <optimized out>
#4  0x00007ffff1a24c00 in pk_backend_resolve_thread (job=<optimized out>, 
    params=<optimized out>, user_data=<optimized out>)
    at pk-backend-aptcc.cpp:685
        search = 0x7fffdc001130
        filters = 262144
        apt = 0x555555837ed0
        pkgs = {<std::vector<pkgCache::VerIterator, std::allocator<pkgCache::VerIterator> >> = std::vector of length 0, capacity 8796093021701, <No data fields>}
#5  0x000055555556e419 in pk_backend_job_thread_setup (
    thread_data=0x555555831390) at pk-backend-job.c:792
        helper = 0x555555831390
#6  0x00007ffff6c0cb45 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#7  0x00007ffff69866fa in start_thread (arg=0x7ffff2431700)
    at pthread_create.c:333
        __res = <optimized out>
        pd = 0x7ffff2431700
        now = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140737257871104, 
                6452119222618554160, 0, 140737488347231, 8388608, 
                93824994891008, -6452131346840682704, -6452139774867144912}, 
              mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, 
            data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
        not_first_call = <optimized out>
        pagesize_m1 = <optimized out>
        sp = <optimized out>
        freesize = <optimized out>
        __PRETTY_FUNCTION__ = "start_thread"
#8  0x00007ffff66bcb5d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109
No locals.
(gdb)

0.8.x is obsolete now unfortunately. See https://www.freedesktop.org/software/PackageKit/pk-download.html for stable and testing versions we support. Sorry!