Is programming knowledge mandatory for an Information Security job?
No, it's not. You can certainly become a pentester or a security architect by focusing your studies on these fields, with only minimal or no programming knowledge.
Does programming knowledge help?
Yes, it does. Because programming in turn teaches a lot about how computers work, and more informally, also how programmers work. This explains why some vulnerability classes still exist, even if they have been known for 20 years now.
Does every job include fixing or customizing software?
No. Pentesters generally don't fix software. They show vulnerabilities and make suggestions on how software can be fixed. Other Information Security jobs may indeed require such suggestions to be implemented, which then basically equates to "being a programmer", and thus requires programming knowledge.
Why do so many Information Security jobs require programming knowledge?
Because Information Security is a vast field, like mammals. Asking "Do Information Security jobs require programming knowledge?" is like asking "Are mammals dangerous?". The answer is, some are and some are not.
As mentioned above, some jobs may require you to do a lot of programming, and thus naturally they will require skills in those programming languages.