HTML Output: Warning: overriding output file extension

[saltorre]

Lizard version: 1.17.13

When I run the lizard tool with the --html flag and with the --output-file ending in .html, I get the error:

Warning: overriding output file extension.

Example:

lizard --length 75 \
		   --CCN 20 \
		   --arguments 3 \
		   --warnings_only \
		   --sort cyclomatic_complexity \
		   --html \
		   --output_file reports/complexity/complexity.html \
		   source

If I run it without the .html extension, the warning goes away but the output file does not have the .html extension despite being formatted like an html file.