Attempt to fix #972

Remove code that causes #972. Most likely it will break something else,
but this is yet to figure.

scripts/test/regression.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# The script runs the regression tests.
+#
+# It's a part of the test process.
+
+set -ex
+
+export PATH="$(yarn bin):$PATH"
+
+env TZ=America/Sao_Paulo babel-node ./test/regression/972.js

src/toDate/index.js

@@ -188,9 +188,6 @@ export default function toDate(argument, dirtyOptions) {
     } else {
       // get offset accurate to hour in timezones that change offset
       offset = getTimezoneOffsetInMilliseconds(new Date(timestamp + time))
-      offset = getTimezoneOffsetInMilliseconds(
-        new Date(timestamp + time + offset)
-      )
     }
 
     return new Date(timestamp + time + offset)

test/regression/972.js

@@ -0,0 +1,14 @@
+// This is a regression test for issue #972: https://github.com/date-fns/date-fns/issues/972
+
+import format from '../../src/format'
+import assert from 'assert'
+
+if (process.env.TZ !== 'America/Sao_Paulo')
+  throw new Error('The test must be run with TZ=America/Sao_Paulo')
+
+const result = format('2018-11-04', 'yyyy-MM-dd HH:mm')
+const expectation = '2018-11-04 01:00'
+assert(
+  result === expectation,
+  `The result should be equal ${expectation} but got ${result}`
+)