No crash found in Corpus Minimization mode

Hi team,

I'm using honggfuzz's Corpus Minimization mode to reduce the size of my test cases set on Ubuntu 18.04. It worked well, and does prevent me from analyzing every test case. But for some projects, for example potrace-1.3([http://potrace.sourceforge.net/](http://potrace.sourceforge.net/)), the number of corpus minimization's result is:

> ------------------------[ 0 days 00 hrs 00 mins 06 secs ]----------------------
> Iterations : 5,075 [5.07k]
> Mode [3/3] : Corpus Minimization
> Target : /home/user/potrace-1.3/src/potrace \_\_\_FILE\_\_\_
> Threads : 1, CPUs: 2, CPU%: 82% [41%/CPU]
> Speed : 823/sec [avg: 845]
> Crashes : 0 [unique: 0, blacklist: 0, verified: 0]
> Timeouts : 0 [1 sec]
> Corpus Size : 0, max: 60,644 bytes, init: 565 files
> Cov Update : 0 days 00 hrs 00 mins 06 secs ago
> Coverage : edge: 0/0 [0%] pc: 0 cmp: 0
> ---------------------------------- [ LOGS ] ------------------/ honggfuzz 2.3 /-
>
>
>
> Entering phase 1/3: Dry Run
> Launched new fuzzing thread, no. #0
> Entering phase 2/3: Switching to the Feedback Driven Mode
> Entering phase 3/3: Corpus Minimization
> Minimized files were copied to '.'
> Terminating thread no. #0, left: 0
> Summary iterations:5075 time:6 speed:845 crashes_count:0 timeout_count:0 new_units_added:0 slowest_unit_ms:18 guard_nb:0 branch_coverage_percent:0 peak_rss_mb:4

The instruction I used is:

> honggfuzz -i ../honggfuzz_inputs/ --output . -M -- /home/user/potrace-1.3/src/potrace \_\_\_FILE\_\_\_

I've used Corpus Minimization mode for a lot of other projects, so I guess that there's no problem with my environment and configuration. And I've run the program potrace directly with several test cases in my input folder (instruction: /home/user/potrace-1.3/src/potrace \_\_\_FILE\_\_\_), and got the output of:

> potrace: warning: ../honggfuzz_inputs/id:000000,sig:11,src:000000,op:havoc,rep:16: premature end of file
> Segmentation fault (core dumped)

That means my inputs are able to crash the program.

However, when I used honggfuzz to minimize my corpus, I got the result that no input caused crash. I'm not sure which step I took wrong, and I'd appreciate it you could help me with the problem. I'll attach my test cases below, which are generated by AFL.

Thank you!
[potrace_inputs.zip](https://github.com/google/honggfuzz/files/6873700/potrace_inputs.zip)

Reproduce the report with the honggfuzz Corpus Minimization command and the attached potrace_inputs.zip corpus on Ubuntu 18.04. Compare the direct potrace crash with honggfuzz's dry-run and minimization output. Done means identifying why the crashing input is excluded or not recognized and documenting or correcting the behavior.

Written by the indexing model from the issue text.