[gnome-battery-bench] Don't add together voltage_now values for multiple batteries

[Owen Taylor <otaylor src gnome org>]

commit b769f9209fdac2d95e2115e8515a8a09cd97e02b
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Jun 30 16:18:35 2015 -0400

    Don't add together voltage_now values for multiple batteries
    
    If there are multiple batteries, it's not possible to compute an
    overall "voltage_now" for the system, so just ignore it.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=747370

 src/power-monitor.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/src/power-monitor.c b/src/power-monitor.c
index 3036815..8946b16 100644
--- a/src/power-monitor.c
+++ b/src/power-monitor.c
@@ -148,6 +148,7 @@ battery_poll(Battery *battery)
     battery->charge_full = -1.0;
     battery->charge_full_design = -1.0;
     battery->capacity_now = -1.0;
+    battery->voltage_now = -1.0;
 
     get_file_contents_double (battery->directory, "energy_now", &battery->energy_now, NULL, NULL);
     if (battery->energy_now >= 0) {
@@ -363,7 +364,6 @@ read_state(GbbPowerMonitor *monitor,
         } else if (battery->charge_now >= 0) {
             add_to (&state->charge_now, battery->charge_now);
             add_to (&state->charge_full, battery->charge_full);
-            add_to (&state->voltage_now, battery->voltage_now);
 
             if (battery->charge_full_design >= 0) {
                 if (n_batteries == 0 || state->charge_full_design >= 0)
@@ -375,6 +375,12 @@ read_state(GbbPowerMonitor *monitor,
             add_to (&state->capacity_now, battery->capacity_now);
         }
 
+        /* state->voltage_now only makes sense if there is a single battery */
+        if (n_batteries == 0)
+            state->voltage_now = battery->voltage_now;
+        else
+            state->voltage_now = -1.0;
+
         n_batteries += 1;
     }