MODULES-1599 Match only on space and tab whitespace after k/v separator

The previous match for \s would also match on newlines.  This caused
existing settings with blank values to have the newline considered part
of the whitespace surrounding the separator.  When such settings are
set with a value, the value ends up on the next line.

Also adding acceptance test for this particular situation.

lib/puppet/util/ini_file.rb

@@ -13,7 +13,7 @@ module Util
       @section_suffix = section_suffix
 
       @@SECTION_REGEX = section_regex
-      @@SETTING_REGEX = /^(\s*)([^#;\s]|[^#;\s].*?[^\s#{k_v_s}])(\s*#{k_v_s}\s*)(.*)\s*$/
+      @@SETTING_REGEX = /^(\s*)([^#;\s]|[^#;\s].*?[^\s#{k_v_s}])(\s*#{k_v_s}[ \t]*)(.*)\s*$/
       @@COMMENTED_SETTING_REGEX = /^(\s*)[#;]+(\s*)(.*?[^\s#{k_v_s}])(\s*#{k_v_s}[ \t]*)(.*)\s*$/
 
       @path = path

spec/acceptance/ini_setting_spec.rb

@@ -72,6 +72,40 @@ describe 'ini_setting resource' do
       it_behaves_like 'has_content', "#{tmpdir}/ini_setting.ini", pp, /four = five\n\n\[one\]\ntwo = three/
     end
 
+    context '=> present for global and section (from previous blank value)' do
+      before :all do
+        if fact('osfamily') == 'Darwin'
+          shell("echo \"four =[one]\ntwo =\" > #{tmpdir}/ini_setting.ini")
+        else
+          shell("echo -e \"four =\n[one]\ntwo =\" > #{tmpdir}/ini_setting.ini")
+        end
+      end
+
+      pp = <<-EOS
+      ini_setting { 'ensure => present for section':
+        ensure  => present,
+        path    => "#{tmpdir}/ini_setting.ini",
+        section => 'one',
+        setting => 'two',
+        value   => 'three',
+      }
+      ini_setting { 'ensure => present for global':
+        ensure  => present,
+        path    => "#{tmpdir}/ini_setting.ini",
+        section => '',
+        setting => 'four',
+        value   => 'five',
+      }
+      EOS
+
+      it 'applies the manifest twice' do
+        apply_manifest(pp, :catch_failures => true)
+        apply_manifest(pp, :catch_changes => true)
+      end
+
+      it_behaves_like 'has_content', "#{tmpdir}/ini_setting.ini", pp, /four = five\n\n\[one\]\ntwo = three/
+    end
+
     context '=> absent for key/value' do
       before :all do
         if fact('osfamily') == 'Darwin'