under Windows, invisible symbols cause a problem with unclosed databases:

From: 	cjc258@cornell.edu
Subject: 	Error when not exporting an optional argument
Date: 	August 31, 2009 12:48:07 PM CDT
To: 	mike.stillman@mac.com
Cc: 	dan@math.uiuc.edu


    Hi,

    I'm Chris, one of Mike's students; I got this [attached] error when I
    failed to export the name of an optional argument for a method. The
    bad news is that when it throws the error, it seems to fail to close
    some files correctly -- thereafter, any additional attempts to
    installPackage fail with the second error shown.

    For reference, I'm using M2 1.2 on Cygwin on Windows XP.

+ M2.exe --no-readline --print-width 45
Macaulay 2, version 1.2
with packages: Elimination, IntegralClosure,
               LLLBases,
               PrimaryDecomposition,
               ReesAlgebra, SchurRings,
               TangentCone

i1 : installPackage"ConnectingHomomorphism"
--installing package ConnectingHomomorphism in .Macaulay2/local/
--using package sources found in /home/Chris Cunningham/
--storing raw documentation in .Macaulay2/local/lib/Macaulay2/ConnectingHomomorphism/cache/rawdocumentation-dcba-4.db
stdio:1:1:(1):[0]: error: can't convert local symbol or invisible global symbol 'Prune' to external string
ConnectingHomomorphism.m2:14:45-14:49: here is the first use of 'Prune'

i2 : installPackage"ConnectingHomomorphism"
--installing package ConnectingHomomorphism in .Macaulay2/local/
--using package sources found in /home/Chris Cunningham/
--storing raw documentation in .Macaulay2/local/lib/Macaulay2/ConnectingHomomorphism/cache/rawdocumentation-dcba-4.db
stdio:2:1:(1):[0]: error: File open error : .Macaulay2/local/lib/Macaulay2/ConnectingHomomorphism/cache/rawdocumentation-dcba-4.db.tmp

