Trying potential fix

src/main/java/at/ac/uibk/gitsearch/service/SearchService.java

@@ -329,15 +329,15 @@ public class SearchService {
                     throw e;
                 }
             }
-            ZipInputStream project = shoppingBasketService.rePackageGitLabProjectZip(
+            InputStream project = shoppingBasketService.rePackageGitLabProjectZip(
                 new ZipInputStream(repositoryArchive),
                 "from project " + exerciseId.getProjectId(),
                 filter,
                 exerciseId.getPath()
             );
-            if (recursive == ExtractionDepth.JUST_PROJECT) return project; else {
+            if (recursive == ExtractionDepth.JUST_PROJECT) return new ZipInputStream(project); else {
                 alreadyTreatedExerciseIds.add(exerciseId); // Side effects are always dangerous :-(
-                return extendZipByChildren(exerciseId, project, user, recursive, alreadyTreatedExerciseIds);
+                return extendZipByChildren(exerciseId, new ZipInputStream(project), user, recursive, alreadyTreatedExerciseIds);
             }
         } catch (GitLabApiException exception) {
             log.error(exception.getMessage());

src/main/java/at/ac/uibk/gitsearch/service/ShoppingBasketService.java

@@ -319,7 +319,7 @@ public class ShoppingBasketService {
      * @return
      * @throws IOException
      */
-    protected ZipInputStream rePackageGitLabProjectZip(
+    protected InputStream rePackageGitLabProjectZip(
         ZipInputStream zipIn,
         String originalLocation,
         String[] filterOut,
@@ -359,15 +359,14 @@ public class ShoppingBasketService {
                     zipInEntry = zipIn.getNextEntry();
                 }
                 zipIn.close();
-                zipOut.close();
             } catch (IOException e) {
-                log.error("Cannot rezip file from {}", originalLocation);
+                log.error("Cannot rezip file from {}", originalLocation, e);
             }
         };
 
         new Thread(rePackage).start();
 
-        return new ZipInputStream(pis);
+        return pis;
     }
 
     public String getExerciseFolderPath(String exercisesPath) {