rmtree() failure on Windows

Houston, we have a problem.

Shown below is an extract from the traces of make installcheck in
contrib. It is decorated with some extra traces I built into
src/port/dirmod.c::rmtree(). It shows quite reproducible failure of
rmtree(), mostly at the rmdir calls, but even more worryingly there are
consistent unlink failures also.

At this stage I have no idea how to go about fixing it.

cheers

andrew

../../src/test/regress/pg_regress init int2 int4 int8 float4 float8 cash
oid timestamp timestamptz time timetz date interval macaddr inet cidr
text varchar char bytea bit varbit numeric
============== dropping database "regression" ==============
DROP DATABASE

../../src/test/regress/pg_regress cube
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/55646":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/55646"

../../src/test/regress/pg_regress dblink
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/69688":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/69688"

../../src/test/regress/pg_regress earthdistance
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72850":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72850"

../../src/test/regress/pg_regress _int
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72914":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72914"

../../src/test/regress/pg_regress ltree
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not unlink
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72987/80059":
No such file or directory
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/72987"

../../src/test/regress/pg_regress pg_trgm
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/80061":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/80061"

../../src/test/regress/pg_regress init md5 sha1 hmac-md5 hmac-sha1
blowfish rijndael crypt-des crypt-md5 crypt-blowfish crypt-xdes
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/82213":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/82213"

../../src/test/regress/pg_regress rtree_gist
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not unlink
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/83241/83277":
No such file or directory
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/83241"

../../src/test/regress/pg_regress seg
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not unlink
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/83283/86678":
No such file or directory
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/83283"

../../src/test/regress/pg_regress tablefunc
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/90065":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/90065"

../../src/test/regress/pg_regress tsearch
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/92694":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/92694"

../../src/test/regress/pg_regress tsearch2
============== dropping database "regression" ==============
DROP DATABASE
WARNING: rmtree could not rmdir
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/92782":
Directory not empty
WARNING: could not remove database directory
"C:/msys/1.0/home/pgrunner/pgbuildfarm/root/HEAD/inst.blurfl/data/base/92782"