  In orbifold gauge theory and gauge-Higgs unification models, gauge anomaly
flows with an Aharonov-Bohm phase $\theta_H$ in the fifth dimension. We analyze
$SU(2)$ gauge theory with doublet fermions in the flat $M^4 \times (S^1/Z_2)$
spacetime and in the Randall-Sundrum (RS) warped space. With orbifold boundary
conditions the $U(1)$ part of gauge symmetry remains unbroken at $\theta_H = 0$
and $\pi$. Chiral anomalies smoothly vary with $\theta_H$ in the RS space.
Anomaly coefficients associated with this anomaly flow are expressed in terms
of the values of the wave functions of gauge fields at the UV and IR branes in
the RS space and parity conditions of fermion fields. Holography in anomaly
flow is observed. Conditions for the anomaly cancellation turn out independent
of $\theta_H$.
