For example:

/home/kehoste/.local/easybuild/software/zlib/1.2.7-goalf-1.1.0-no-OFED/lib/libz.so.1: no version information available

also see http://superuser.com/questions/305055/how-to-diagnosis-and-resolve-usr-lib64-libz-so-1-no-version-information-avail

This is caused by programs/libraries that both use zlib and other (system) libraries at the same time.

The linker ld notices that another library was linked against another version of zlib, and spit out this error message.

Since the error message is printed every time libz.so is loaded, this is annoying.
Also, sometimes it breaks things, for example during the PETSc build (it thinks the ar archiver doesn't work properly because the "no version information available" error message is being printed when ar is tested).