Hooks: avoid problems with backslashes in paths

Calling sh -c with a script path containing backslashes may fail since
the shell may try to process them as escape characters.

Instead of calling

  sh.exe -c 'C:\path\script "$@"' 'C:\path\script' other args

call

  sh.exe -c '$0 "$@"' 'C:\path\script' other args

which avoids this escape processing.

Note that this is not specific to Windows. If the path or the script
name contain backslashes, this also occurs on Unix.

Bug: 558577
Change-Id: I47d63db6f8644f956c55c42b07dbcad7d7f305aa
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java

@@ -261,7 +261,7 @@ public class FS_POSIX extends FS {
 		List<String> argv = new ArrayList<>(4 + args.length);
 		argv.add("sh"); //$NON-NLS-1$
 		argv.add("-c"); //$NON-NLS-1$
-		argv.add(cmd + " \"$@\""); //$NON-NLS-1$
+		argv.add("$0 \"$@\""); //$NON-NLS-1$
 		argv.add(cmd);
 		argv.addAll(Arrays.asList(args));
 		ProcessBuilder proc = new ProcessBuilder();

org.eclipse.jgit/src/org/eclipse/jgit/util/FS_Win32_Cygwin.java

@@ -149,7 +149,7 @@ public class FS_Win32_Cygwin extends FS_Win32 {
 		List<String> argv = new ArrayList<>(4 + args.length);
 		argv.add("sh.exe"); //$NON-NLS-1$
 		argv.add("-c"); //$NON-NLS-1$
-		argv.add(cmd + " \"$@\""); //$NON-NLS-1$
+		argv.add("$0 \"$@\""); //$NON-NLS-1$
 		argv.add(cmd);
 		argv.addAll(Arrays.asList(args));
 		ProcessBuilder proc = new ProcessBuilder();