Add mingw64 dir to ssh location guesser - windows git 2.8.0

Implement ssh executable test in CliGitAPIImplTest, not applicable
to JGit.

May help [JENKINS-30045], [JENKINS-28943], [JENKINS-25297], & [JENKINS-21806]

src/main/java/org/jenkinsci/plugins/gitclient/CliGitAPIImpl.java

@@ -1643,6 +1643,14 @@ private File getSSHExeFromGitExeParentDir(String userGitExe) {
             if (sshexe != null && sshexe.exists()) {
                 return sshexe;
             }
+            sshexe = getSSHExeFromGitExeParentDir(gitPath.replace("/mingw64/", "/").replace("\\mingw64\\", "\\"));
+            if (sshexe != null && sshexe.exists()) {
+                return sshexe;
+            }
+            sshexe = getSSHExeFromGitExeParentDir(gitPath.replace("/mingw64/bin/", "/usr/bin/").replace("\\mingw64\\bin\\", "\\usr\\bin\\"));
+            if (sshexe != null && sshexe.exists()) {
+                return sshexe;
+            }
         }
 
         throw new RuntimeException("ssh executable not found. The git plugin only supports official git client http://git-scm.com/download/win");

src/test/java/org/jenkinsci/plugins/gitclient/CliGitAPIImplTest.java

@@ -3,6 +3,8 @@
 import java.io.File;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
+import static junit.framework.TestCase.assertTrue;
+import org.apache.commons.lang.SystemUtils;
 
 /**
  * @author <a href="mailto:nicolas.deloof@gmail.com">Nicolas De Loof</a>
@@ -246,6 +248,16 @@ public void test_git_version_ubuntu_14_04_ppa_2_3_5() {
         doTest("git version 2.3.5", versions);
     }
 
+    /* Not implemented in JGit because it is not needed there */
+    public void test_git_ssh_executable_found_on_windows() throws Exception {
+        setTimeoutVisibleInCurrentTest(false);
+        if (!SystemUtils.IS_OS_WINDOWS) {
+            return;
+        }
+
+        assertTrue("ssh.exe not found", w.cgit().getSSHExecutable().exists());
+    }
+
     @Override
     protected String getRemoteBranchPrefix() {
         return "remotes/";

src/test/java/org/jenkinsci/plugins/gitclient/GitAPITestCase.java

@@ -265,7 +265,7 @@ public IGitAPI igit() {
         }
     }
 
-    private WorkingArea w;
+    protected WorkingArea w;
 
     WorkingArea clone(String src) throws Exception {
         WorkingArea x = new WorkingArea();
@@ -3890,17 +3890,6 @@ public void test_longpaths_disabled() throws Exception {
         assert_longpaths(w, false);
     }
 
-    @NotImplementedInJGit
-    /* Not implemented in JGit because it is not needed there */
-    public void test_git_ssh_executable_found_on_windows() throws Exception {
-        setTimeoutVisibleInCurrentTest(false);
-        if (!SystemUtils.IS_OS_WINDOWS) {
-            return;
-        }
-
-        assertTrue("ssh.exe not found", w.cgit().getSSHExecutable().exists());
-    }
-
     /**
      * Returns the prefix for the remote branches while querying them.
      * @return remote branch pregix, for example, "remotes/"