Comment 2 for bug 510940

"It is highly recommended, that all input files, i.e. the ConTEXt source and other included files such as image files, have only the letters a–z, digits and dashes in their names, that is in the names of their full paths, otherwise you can easily get into problems. Especially the characters *, ?, the space character and some more are known to cause problems, sometimes because of ConTEXt itself (internal pattern matching), sometimes because of issues with the underlying operating system. The dot ‘.' is somewhat special: it's used to separate the suffix from the rest of the file-name, but at other places in the path it can cause trouble just like ‘*' or ‘?'." (http://pmrb.free.fr/contextref.pdf)

This is IMHO a "Won't Fix".
As a workaround you can try "context" instead of "texexec", seem to work on your example, but no guarantees.