Warn if configured cookie file is missing

We logged a stack trace if the configured http.cookieFile was missing.
Instead only log a warning.

Bug: 548081
Change-Id: I42e39f5ad8ffce7b43162e5068f60af073b8a126
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties

@@ -459,6 +459,7 @@ mismatchOffset=mismatch offset for object {0}
 mismatchCRC=mismatch CRC for object {0}
 missingAccesskey=Missing accesskey.
 missingConfigurationForKey=No value for key {0} found in configuration
+missingCookieFile=Configured http.cookieFile ''{0}'' is missing
 missingCRC=missing CRC for object {0}
 missingDeltaBase=delta base
 missingForwardImageInGITBinaryPatch=Missing forward-image in GIT binary patch

org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java

@@ -520,6 +520,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String mismatchCRC;
 	/***/ public String missingAccesskey;
 	/***/ public String missingConfigurationForKey;
+	/***/ public String missingCookieFile;
 	/***/ public String missingCRC;
 	/***/ public String missingDeltaBase;
 	/***/ public String missingForwardImageInGITBinaryPatch;

org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/http/NetscapeCookieFile.java

@@ -344,6 +344,11 @@ public final class NetscapeCookieFile {
 		final int maxStaleRetries = 5;
 		int retries = 0;
 		File file = getPath().toFile();
+		if (!file.exists()) {
+			LOG.warn(MessageFormat.format(JGitText.get().missingCookieFile,
+					file.getAbsolutePath()));
+			return new byte[0];
+		}
 		while (true) {
 			final FileSnapshot oldSnapshot = snapshot;
 			final FileSnapshot newSnapshot = FileSnapshot.save(file);