Issue with copy images to output directory

Coping images linked in rst files are giving an error:

[error] Unable to write file "/guides/docs/cli/first-docs.png", Impossible to create the root directory "/opt/project/build/docs/guides/docs/cli". mkdir(): File exist

Expected behavior

Image should be linked correctly

Actual behavior

Error is reported image is not copied. The output html looks fine.

Steps to reproduce the problem

1. add an image directive to an rst file and link it to an existing image
2. run phpdoc

Start by reproducing the issue with an rst file that uses an image directive pointing to an existing image, then run phpdoc and inspect the reported output path. Investigate the image-copying entry point responsible for creating the output directory. Done means phpdoc completes without the mkdir error and the image is copied and linked correctly in the generated HTML.