@jeffkaufman 
Trying to land this on master, but I need some more time.
Load testing on master without this patch, I get the following backtrace, which I think needs looking in to first:
```
Program received signal SIGSEGV, Segmentation fault.
0x0000000000410eb2 in ngx_log_error_core (level=8, log=0x12d01d0, err=0, fmt=0xbf2b63 "reusable connection: %ui") at src/core/ngx_log.c:94
94          if (log->file->fd == NGX_INVALID_FILE) {
(gdb) bt
#0  0x0000000000410eb2 in ngx_log_error_core (level=8, log=0x12d01d0, err=0, fmt=0xbf2b63 "reusable connection: %ui") at src/core/ngx_log.c:94
#1  0x000000000041c076 in ngx_reusable_connection (c=0x7ffff7e4efd0, reusable=0) at src/core/ngx_connection.c:968
#2  0x000000000041c329 in ngx_close_connection (c=0x7ffff7e4efd0) at src/core/ngx_connection.c:924
#3  0x00000000004879dd in ngx_psol::(anonymous namespace)::ps_connection_read_handler (ev=<optimized out>) at ../ngx_pagespeed/src/ngx_pagespeed.cc:1129
#4  0x000000000042f96a in ngx_epoll_process_events (cycle=0x11f29a0, timer=<optimized out>, flags=<optimized out>) at src/event/modules/ngx_epoll_module.c:683
#5  0x0000000000426bc1 in ngx_process_events_and_timers (cycle=0x11f29a0) at src/event/ngx_event.c:249
#6  0x000000000042f1d9 in ngx_single_process_cycle (cycle=0x11f29a0) at src/os/unix/ngx_process_cycle.c:315
#7  0x000000000041069b in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:409
```