This was seen in WMF production during a train deployment, where namespacing of classes,
which had been serialized (for example CacheTime), along with our PSR-4 definitions may result
in cases where PHP tries to load the same PHP file more than once. Combined with non obvious
error messages, require_once gives us better behaviour and error messages.
More explicitly:
In T378006, the autoloader is entered from class_exists(), and the class has a filename
resolvable with PSR-4 which is already loaded by a non-PSR-4 class name. Using require_once
would allow class_exists() to return false in that case.
In T372500, the autoloader is entered from unserialize(). It looks like require_once would
just give you a more informative error message.
Bug: T378006
Bug: T372500
Change-Id: I928f29198af9baf81a3cae604b3adf41595c2176
(cherry picked from commit 03dd4ae7ae0e2ce7e45f0bf2cb913642eef842a8)
e4bee84a27