Incorrect selections with numeric or position variables that are used multiple times
If selections use variables with a numeric value (e.g., an arithmetic expression), and those variables are referenced more than once, and the variable needs to be evaluated for different set of atoms in different contexts, this in some cases results in an out-of-bounds memory access and/or wrong selection.
As a separate issue, variables with a position value that are referenced more than once cause seg faults.
Found in tests added in https://gerrit.gromacs.org/#/c/1436 and fixed in the same commit for 5.0. The fix should be backported to 4.5.