Enhance the file filtering capabilities.
We now allow filtering through either pipes or pairs of temporary
files. The latter appear to be mandatory for use on Windows.
#!/bin/shmkdir acd ahg initecho foo > bhg add bhg ci -m "b" -d "0 0"chmod -w .hgcd ..hg clone a bcd bhg verifycd ..chmod +w a/.hg # let test clean up