At document of REST API v3, parameters are added using +
. So how about the following modification?
From :
https://api.github.com/search/repositories?q=mysql&created:<2009-04-11&order=asc
https://api.github.com/search/repositories?q=mysql&created:>=2013-04-11&order=asc
To :
https://api.github.com/search/repositories?q=mysql+created:<2009-04-11&order=asc
https://api.github.com/search/repositories?q=mysql+created:>=2013-04-11&order=asc
If I misunderstand your question, I'm sorry.
Edit :
When you want to retrieve the data using curl, please use as follows. In this case, please enclose the URL using double quotations. The URL in this sample is from your comments.
curl "https://api.github.com/search/repositories?q=python+created:%3E2009-04-11&page=1"
or
curl "https://api.github.com/search/repositories?q=python+created:>2009-04-11&page=1"