Note 2 myself just in case I’ll stumble into this again:

I’ve tried to add a javascript file (jquery-1.3.2.min.js) to clearcase, and got the following response:

jquery-1.3.2.min.js is not a 'text file': it contains a line exceeding 8000 bytes. Use a different type manager (such as compressed file).
Type manager "text_file_delta" failed create_version operation.

Huh? Anyway, this can be solved by

$ cleartool chtype -nc compressed_file jquery-1.3.2.min.js


Change version manager and reconstruct all version for "jquery-1.3.2.min.js"? [no] y
Changed type of element "jquery-1.3.2.min.js" to "compressed_file".

Afterwards, the file can be checked in without problems.