[basic.start.static]/2

Constant initialization is performed if a variable or temporary object with static or thread storage duration is initialized by a constant initializer ([expr.const]) for the entity. If constant initialization is not performed, a variable with static storage duration ([basic.stc.static]) or thread storage duration ([basic.stc.thread]) is zero-initialized ([dcl.init]). Together, zero-initialization and constant initialization are called static initialization; all other initialization is dynamic initialization. All static initialization strongly happens before ([intro.races]) any dynamic initialization. [ Note: The dynamic initialization of non-local variables is described in [basic.start.dynamic]; that of local static variables is described in [stmt.dcl]. — end note ]

To verify this, see line # 5735 in the committed pull request:

5735 \indextext{initialization!runtime}%

AFAICT this is basically saying that zero-initialization is somehow related to run-time initialization, which doesn't seem to be correct.

To correct this, simply reverse the content of lines 6067 and 6068 in basic.tex.