Add method to retrieve branch name from repository

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/GitUtil.java

@@ -499,6 +499,33 @@ public final class GitUtil
     return ref;
   }
 
+  public static String getRepositoryHeadBranchName(org.eclipse.jgit.lib.Repository repo) {
+    Map<String, Ref> refs = repo.getAllRefs();
+    Ref lastHeadRef = null;
+
+    for (Map.Entry<String, Ref> e : refs.entrySet()) {
+      String key = e.getKey();
+
+      if (REF_HEAD.equals(key)) {
+        if (e.getValue().isSymbolic() && isBranch(e.getValue().getTarget().getName())) {
+          return getBranch(e.getValue().getTarget());
+        }
+      } else if (key.startsWith(REF_HEAD_PREFIX)) {
+        if (REF_MASTER.equals(key.substring(REF_HEAD_PREFIX.length()))) {
+          return REF_MASTER;
+        } else {
+          lastHeadRef = e.getValue();
+        }
+      }
+    }
+
+    if (lastHeadRef == null) {
+      return null;
+    } else {
+      return getBranch(lastHeadRef);
+    }
+  }
+
   /**
    * Method description
    *
@@ -648,7 +675,7 @@ public final class GitUtil
 
     return tagName;
   }
-  
+
   /**
    * Method description
    *

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/AbstractGitCommand.java

@@ -97,9 +97,9 @@ public class AbstractGitCommand
     return commit;
   }
 
-  protected String getBranchNameOrDefault(String requestedBranch) {
+  protected String getBranchNameOrDefault(Repository gitRepository, String requestedBranch) {
     if ( Strings.isNullOrEmpty(requestedBranch) ) {
-      return getDefaultBranchName();
+      return getDefaultBranchName(gitRepository);
     } else {
       return requestedBranch;
     }
@@ -115,12 +115,12 @@ public class AbstractGitCommand
     return head;
   }
 
-  protected String getDefaultBranchName() {
+  protected String getDefaultBranchName(Repository gitRepository) {
     String defaultBranchName = repository.getProperty(GitConstants.PROPERTY_DEFAULT_BRANCH);
     if (!Strings.isNullOrEmpty(defaultBranchName)) {
       return defaultBranchName;
     } else {
-      return null;
+      return GitUtil.getRepositoryHeadBranchName(gitRepository);
     }
   }
 

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitLogCommand.java

@@ -208,7 +208,7 @@ public class GitLogCommand extends AbstractGitCommand implements LogCommand
         }
 
         ObjectId head = getBranchOrDefault(repository, request.getBranch());
-        String branch = getBranchNameOrDefault(request.getBranch());
+        String branch = getBranchNameOrDefault(repository,request.getBranch());
 
         if (head != null) {
           if (startId != null) {