Answer
The current through $R_1$ is the same as it was previously.
Work Step by Step
Let $\Delta V$ be the potential difference across the battery.
Initially, the potential difference across $R_1$ is $\Delta V$
After $R_2$ is added in parallel, the potential difference across each resistor is $\Delta V$
Therefore, the potential difference across $R_1$ is the same as it was previously.
Initially, the current through $R_1$ is $~~i_1 = \frac{\Delta V}{R_1}$
After $R_2$ is added in parallel, the current through $R_1$ is still $~~i_1 = \frac{\Delta V}{R_1}$
The current through $R_1$ is the same as it was previously.
