broken search field of python-sphinx website on reathedocs.org

I discovered that the search function of the latest version of my website eswp3.org hosted on readthedocs.org does not work anymore. I use the default search functionality of the python-sphinx html theme sphinx_rtd_theme. I use the default makefile to build the html files.

Some possible bug cause investigation:

The search field of website versions v1.1 and website version v1.0 is broken.
In website version V0.1 the search field is working. (Versions may be switched with the field in the bottom left on the website.)
After rebuilding the website sources v1.0 and on the local file system the search field of v1.0 does not work, the search field of v0.1 does work.
Comparing the website source v1.0 and v0.1 lead to following differences:

To the diff screenshot

I checked the differences in conf.py but i did not catch critical differences.
I deleted the files in _build/html and rebuilt the files with the python-sphinx default make target make html in the root directory eswp3/ on my local file system. No problems regarding indexing have been printed.
Unfortunately the search field in the generated version is also not working.

What did i miss? Do i have to consider possible differences of the python-sphinx versions used in the different builds?

Thanks a lot in advance.

Solution

Some files edited on windows machines have not been commited to github as UTF-8 format files but WINDOWS-1252 format files initially or after file edits. Converting all *.rst files to UTF-8 did the job (e.g. by converting all *.srt files of the current directory on UNIX into a subfolder /utf-8 using find . -name "*.rst" -exec iconv -f WINDOWS-1252 -t UTF-8 {} -o utf-8/{} \;).