pg_upgrade and log file output on Windows

Has anyone successfully used pg_upgrade 9.0 with -l (log) on Windows?

I received a private email bug report that pg_upgrade 9.0 does not work
with the -l/log option on Windows.  The error is:
Analyzing all rows in the new cluster""c:/MinGW/msys/1.0/home/edb/inst/bin/vacuumdb" --port 55445 --username "edb"
--all--analyze>> c:/MinGW/msys/1.0/home/edb/auxschedule/test.log 2>&1"The process cannot access the file because it is
beingused by anotherprocess.
 

What has me confused is this same code exists in pg_migrator, which was
fixed to work with -l on Windows by Hiroshi Saito with this change:
    /*     * On Win32, we can't send both server output and pg_ctl output     * to the same file because we get the
error:    * "The process cannot access the file because it is being used by another process."     * so we have to send
pg_ctloutput to 'nul'.     */    sprintf(cmd, SYSTEMQUOTE "\"%s/pg_ctl\" -l \"%s\" -D \"%s\" "    "-o \"-p %d -c
autovacuum=off-c autovacuum_freeze_max_age=2000000000\" "            "start >> \"%s\" 2>&1" SYSTEMQUOTE,
bindir,ctx->logfile, datadir, port,#ifndef WIN32             ctx->logfile);#else             DEVNULL);#endif
 

The fix was not to use the same log file and output file for pg_ctl. 
But as you can see, the pg_ctl and vacuumdb code is unchanged:
   prep_status(ctx, "Analyzing all rows in the new cluster");   exec_prog(ctx, true,             SYSTEMQUOTE
"\"%s/vacuumdb\"--port %d --username \"%s\" "             "--all --analyze >> %s 2>&1" SYSTEMQUOTE,
ctx->new.bindir,ctx->new.port, ctx->user, ctx->logfile);
 

I can't figure out of there is something odd about this user's setup or
if there is a bug in pg_upgrade with -l on Windows.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +