g_assert() uses G_LIKELY(), which in turn uses _G_BOOLEAN_EXPR().
As glib's version of _G_BOOLEAN_EXPR() uses a local variable
_g_boolean_var_, we cannot nest a G_LIKELY() inside a G_LIKELY(),
or inside a g_assert(), or a g_assert() inside a g_assert().
Workaround that, by redefining the macro.
I already encountered this problem before, when having a nm_assert()
inside a ({...}) block, inside a g_assert(). Then I just avoided that
combination, but this situation is quite easy to encounter.
6b904a51ee