[BUG] No workflows generated for trivial input/output

[524D]

Description

On the current Workflomics live site, specifying input and outputs that should result in trivial workflow with a single tool does not work. No workflows are found. I assume this is caused by APE, therefore submitting in this repo.

Steps to Reproduce

1. In the Workflomics web interface, use the "sample data" to set initial values
2. Change the output to "Peptide Identification/pepXML"
3. Change the workflow length to min=1 max=2
4. Run to generate workflows

Note: the problem was initially found by trying to generate a workflow for "wcloud", but since we will change the input type of that tool this may not be the ideal testcase.

Expected Behavior

At least a workflow with just "Comet" should be generated, as it has exactly these inputs/output. Probably more search engines also match.

Actual Behavior

No workflows are found.