Small analyze_prs improvements

Don't error out if num users provided is greater than
returned total.

Drop users with 0 total prs.

scripts/analyze_prs.py

@@ -70,6 +70,12 @@
             total_revup += 1
             users[name][1] += 1
 
+    # Delete users from the list with 0 prs
+    for user in list(users.keys()):
+        if users[user][0] == 0:
+            del users[user]
+    args.num_users = min(args.num_users, len(users))
+
     print("Total PRs: {}".format(total))
     print("Total revup PRs: {}".format(total_revup))
     print(