nexus: Move persistent data

When any configuration is done to the nexus server is persists that data
to the sonatype-work directory. Also all maven artifacts are downloaded
into that directory too. So if you want to have that same setup after
upgrading, the sonatype-work directory needs to be somewhere common all
versions. This commit patches nexus to look for that data in var/nexus.

Closes Homebrew/homebrew#19361.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/nexus.rb

@@ -2,13 +2,17 @@ require 'formula'
 
 class Nexus < Formula
   homepage 'http://www.sonatype.org/'
-  url 'http://download.sonatype.com/nexus/oss/nexus-2.3.1-01-bundle.tar.gz'
-  version '2.3.1-01'
+  url 'http://download.sonatype.com/nexus/oss/nexus-2.3.1-bundle.tar.gz'
   sha1 'f064052500223e7af3e3323b6bc9fb7c047ac0e1'
 
+  # Put the sonatype-work directory in the var directory, to persist across version updates
+  def patches
+    DATA
+  end
+
   def install
     rm_f Dir['bin/*.bat']
-    libexec.install Dir["nexus-#{version}/*"]
+    libexec.install Dir["nexus-2.3.1-01/*"]
     bin.install_symlink libexec/'bin/nexus'
   end
 
@@ -32,4 +36,26 @@ class Nexus < Formula
     </plist>
     EOS
   end
+
+  def caveats; <<-EOS.undent
+    If you are upgrading nexus for the first time, and old version is less than 2.3.1, then
+    you will need to copy the sonatype-work directory from:
+      #{HOMEBREW_PREFIX}/Cellar/#{name}/<old version>/
+    to
+      #{var}
+    EOS
+  end
 end
+
+__END__
+diff --git a/nexus-2.3.1-01/conf/nexus.properties b/nexus-2.3.1/conf/nexus.properties
+index df89251..23b536b 100644
+--- a/nexus-2.3.1-01/conf/nexus.properties
++++ b/nexus-2.3.1-01/conf/nexus.properties
+@@ -22,5 +22,5 @@ nexus-webapp=${bundleBasedir}/nexus
+ nexus-webapp-context-path=/nexus
+
+ # Nexus section
+-nexus-work=${bundleBasedir}/../sonatype-work/nexus
++nexus-work=HOMEBREW_PREFIX/var/nexus
+ runtime=${bundleBasedir}/nexus/WEB-INF