tests/test_family_bump_fetch_refspecs.py: two docstrings say a mirror into origin/ was carried on #946's first head, where only a tag refspec in a folder was #997

Goal: the two docstrings say what each refspec did on #946's first head, 4e1aa24a. Text only; no code changes.

Filed by lane openRepoShape-4 from RV946's round-2 NIT N6 on #946 (issuecomment-6266641009). It was left out of #946 so the reviewed head 5d5d06bb could land as reviewed.

State, at 5d5d06bb:

• The module docstring, tests/test_family_bump_fetch_refspecs.py:23-25, says a tag refspec and a mirror into origin/ "are now left out (RV946's S1 and S2)".
• The reachability row's docstring, :242-244, says both runs pinned the commit "in a folder or a mirror (origin/tags/v-release) on family.py: bump's fetch no longer moves the mount's own branches, works where the mount maps tags into origin/ instead of telling the person to fix the network, reads its refspecs with git config --list -z, and asks git remote get-url origin first, so a mount with no origin is not fetched from a path of that name (#905) #946's first head too (RV946's S1 and S2)".

What is true: only the tag refspec in a folder (+refs/tags/*:refs/remotes/origin/tags/*) was carried on 4e1aa24a (S1). Round 0 already left the mirror (+refs/*:refs/remotes/origin/*) out by its destination clause; S2 asked only for a test of it. RV946 measured this: against 4e1aa24a's family.py, the new file fails only the two [tags-in-a-folder] rows, and both [mirror-into-origin] rows pass.

Direction.

• :23-25: say the tag refspec in a folder is now left out (S1), and that the mirror was already left out and now has rows (S2).
• :242-244: RV946's wording, "in a folder on family.py: bump's fetch no longer moves the mount's own branches, works where the mount maps tags into origin/ instead of telling the person to fix the network, reads its refspecs with git config --list -z, and asks git remote get-url origin first, so a mount with no origin is not fetched from a path of that name (#905) #946's first head too (S1); the mirror (S2) had no test".
• Check: git grep -n "first head" tests/test_family_bump_fetch_refspecs.py.

Size: XS.

Lane: openreposhape-4 (openRepoShape-4)