In preprocess2, filtered topics result in "failed to transform file" errors

[chrispy-snps]

Expected Behavior

If I have topics that are filtered out in a map:

the transformation should cleanly ignore the filtered topics.

Actual Behavior

When preprocess2 is used, processing attempts to access the filtered-out topic files:

Error: Failed to process XML filter: Failed to transform file:/.../9406ab68e62ed15a801de18c7736f1beb2fb1fc9.dita: /.../9406ab68e62ed15a801de18c7736f1beb2fb1fc9.dita (No such file or directory)
Error: A source of type net.sf.saxon.lib.EmptySource is not supported in this environment
Error: Failed to transform document: Failed to transform document: A source of type net.sf.saxon.lib.EmptySource is not supported in this environment
Error: A source of type net.sf.saxon.lib.EmptySource is not supported in this environment
Error: Failed to transform document: Failed to transform document: A source of type net.sf.saxon.lib.EmptySource is not supported in this environment

The testcase uses branch filtering for convenience, but the issue also occurs when filtering is specified using --filter.

Possible Solution

Not sure.

Steps to Reproduce

1. Download and extract the following testcase:
   4383.zip
2. Run the following command:
   dita -i map.ditamap -f html5

Environment

• DITA-OT version: 4.1.2, 4.2-prerelease
• Operating system and version: Linux
• How did you run DITA-OT? dita command
• Transformation type: pdf2, html5 in the DITA-OT 4.2 prerelease

[chrispy-snps]

Can the priority for this be raised? We use filtering heavily, and this will obscure real issues with the content.

[chrispy-snps]

@jelovirt - thanks very much for the fix!