fixed Issue #181

[manikyarathore]

This change fixes an issue where setting preferenceDepthHops = 0 (intended to enable depth first crawling) caused Heritrix to reject seed URLs immediately with fetch status -50.

The problem was in TooManyHopsDecideRule, where a negative maxHops value (used internally for DFS) caused all URIs including seeds with hop count 0 to be evaluated as exceeding the hop limit. As a result, no crawling occurred.

The fix updates the hop limit evaluation logic to:
Treat negative maxHops values as “no hop limit”
Always allow seed URLs (hopCount == 0) to pass the rule
This restores the documented DFS behavior while preserving existing behavior for normal breadth first crawls.

[ato]

I tested this change but still see status -50. Here's what I tried:

1. New test job with default config.
2. Set operator contact URL.
3. Add seed: http://example.com/
4. Set preferenceDepthHops = 0
5. Launch and unpause.

The seed immediately failed with status -50:

2025-12-21T00:56:28.083Z   -50          - http://example.com/ - - unknown #007 - - - 30t

After that Heritrix kept issuing DNS requests without making progress:

2025-12-21T00:56:28.642Z     1         89 dns:example.com P http://example.com/ text/dns #007 20251221005628084+38 sha1:AMSS4LNS6TWYXNFYW4R7XGKJXKYXKOJY - -
2025-12-21T00:56:31.702Z     1         89 dns:example.com P http://example.com/ text/dns #007 20251221005631701+0 sha1:TTE4YPYC72NGJLRXP7QQE3TBXL2PSP4N - -
2025-12-21T00:56:34.754Z     1         89 dns:example.com P http://example.com/ text/dns #007 20251221005634753+0 sha1:OX44Z2HCQXQSC23I5QCFKB53ZMNEQV3E - -
2025-12-21T00:56:37.792Z     1         89 dns:example.com P http://example.com/ text/dns #007 20251221005637789+1 sha1:7KGPM4NIAU7KD5PFX3ZCS6DY75LX3QXR - -
2025-12-21T00:56:40.852Z     1         89 dns:example.com P http://example.com/ text/dns #007 20251221005640851+0 sha1:47DAR5REXOEHH4AXGK3EEAGGME5UK5Y2 - -

I also set a breakpoint in TooManyHopsDecideRule.evaluate() and it was never hit, which makes me think this rule is probably not involved and the root cause of #181 is likely elsewhere.