less SEGV with multiple non-existent files

Binary package hint: less

If less encounters two nonexistant files then an existing file it will segfault.

To reproduce, run this command line then press :n a few times:
F="/tmp/a1 /tmp/a2 /tmp/a3"; touch /tmp/a4; touch $F; ( sleep 0.5; rm $F ) & LD_PRELOAD=/lib/libSegFault.so less $F /tmp/a4

Note also, just before it crashes (between the final colon and n presses) it says:
@J º : No such file or directory (press RETURN)

Backtrace (anchored at 00400000):
#0 0x000000000040b675 in ?? ()
#1 0x00000000004098a1 in edit_ifile ()
#2 0x0000000000409a3a in edit_istep ()
#3 0x000000000040764f in ?? ()
#4 0x00000000004021e6 in ?? ()
#5 0x00007ffd718de1c4 in __libc_start_main () from /lib/libc.so.6
#6 0x0000000000401c39 in ?? ()
#7 0x00007fff7a0787f8 in ?? ()
#8 0x0000000000000000 in ?? ()

Frame 1 looks like this:
edit_ifile(ifile)
...
               if (alt_filename != NULL)
               {
                       close_altfile(alt_filename, filename, alt_pipe); // <====
                       free(alt_filename);
               }
               del_ifile(ifile);
               free(qopen_filename);