The __construct function in SchemaCache generates an empty $cid, at least on my setup:
Mamp pro 2.0 - php 5.3.6 - see screenshot underneath. I'm seeing this in both D8 and D.

Patch attached generates the cid as 'schema:runtime:1'
| Comment | File | Size | Author |
|---|---|---|---|
| #5 | 1289364-after.patch | 1.51 KB | swentel |
| #2 | 1289364-before.patch | 1009 bytes | swentel |
| #2 | 1289364-after.patch | 1.5 KB | swentel |
| empty_cid.patch | 529 bytes | swentel | |
| empty-cid.png | 25.73 KB | swentel |
Comments
Comment #1
chx commentedWell spotted! tests?
Comment #2
swentel commentedAdded a very simple test - the before patch will fail, the after should pass.
Should cache_set also do nothing if the $cid is empty ?
Comment #3
catchLooks good, nice find!
Comment #4
dries commentedCommitted to 8.x. Thanks!
Comment #5
swentel commentedHere's the 7.x version.
Comment #7
swentel commentedHmm, ok, I don't really see why this might trigger an exception there - just trying another review, maybe there's been a slight glitch - will ping one of the testbot maintainers afterwards (or I should try it out locally first maybe)
Comment #8
swentel commented#5: 1289364-after.patch queued for re-testing.
Comment #9
catchLooks fine for 7.x too.
Comment #10
webchickCommitted and pushed to 7.x. Thanks!
Comment #11
webchick