I've pushed your modification to sepheaders.c but have a question for you about the modification to lib1900.c:
Is the check for 'handlenum < num_handles' needed in that second if statement, in order to pass cppcheck, given that the same check happens a few lines up and the values of 'handlenum' and 'num_handles' are not modified in between the two if statements?
Unless I've missed something I don't think it is needed from a logic point of view.
I'll prepare a patch on your behalf and push it.
Fyi: Daniel has started to use Coverity to scan the source code over recent months and I've just been looking at the cppcheck website, whilst compiling various patches, so I will try cppcheck myself over the next few days.