Don't reduce the weight of exits selected as fallback directories

When selecting exits as fallback directories, don't reduce
their weights.

Closes ticket #17888.

changes/bug17888

@@ -0,0 +1,6 @@
+  o Minor fixes (fallback directories):
+    - When selecting exits as fallback directories, don't reduce
+      their weights. (Several operators report having exits with
+      spare capacity.) 
+      Closes ticket #17888. Patch by "teor". Not in any released
+      version of tor.

scripts/maint/updateFallbackDirs.py

@@ -98,7 +98,7 @@ MIN_FALLBACK_COUNT = 100
 ## Fallback Weight Settings
 
 # Any fallback with the Exit flag has its weight multipled by this fraction
-EXIT_WEIGHT_FRACTION = 0.2
+EXIT_WEIGHT_FRACTION = 1.0
 
 # If True, emit a C #error if we can't satisfy various constraints
 # If False, emit a C comment instead