Alexander P., can you please evaluate if it is a showstopper or not?

Yes, it's a showstopper as 'Build Package' command breaks the project. After that any action with the project causes NPE (see bug #186288).

*** Bug 186288 has been marked as a duplicate of this bug. ***

Can't reproduce on any platform. Will keep trying though. 

Here is the offending code:
1309        String outputFileName = projectDescriptor.getBaseDir() + '/' + MakeConfiguration.NBPROJECT_FOLDER + '/' + "Package-" + conf.getName() + ".bash"; // UNIX path // NOI18N
...
1321        FileOutputStream os = null;
1322        try {
1323            os = new FileOutputStream(outputFileName);
1324        } catch (Exception e) {
1325           // FIXUP
1326        }
1327        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os));

Looks like the os is null (or bad) so something must be wrong with outputFileName path or permissions. new FileOutputStream will fail if file cannot be opened (or created) and or cannot be written to.

Questions:
1) is it reproducible? Please start with fresh userdir and use a 'good' build.
2) if reproducible, is it on any platform?
3) I noticed the pc is running Russian locale. Is this true? Could this be the problem?

I added a better check and also now reports the exception if it happens. Please try again and report back what the exception is. The exception is in the log file.

Bug is reproducible on *Windows* only.

Can you please answer questions 1-3 in comment #4? I need to know more about how to reproduce it...

1 - it's reproducible in the fresh good build with a fresh userdir
2 - it's reproducible only on Windows
3 - I strongly doubt that it depends on locale as I use only paths containing english characters without spaces.

Steps to reproduce:
- create Welcome using cygwin tool collection
- build it, OK
- call More Build Commands --> Build Package
- build is OK but the packaging never ends
- terminate build (packaging)
- open project properties and try to change any property or just call project context menu and move mouse across the context menu
Result: NPE (see bug #186288) occurs.

OK, now I can reproduce it. Will investigate....

I believe it is an execution problem and not related to the contents of the actual package script:

1) CND 6.9 generated scripts work fine with a CND 6.8
2) CND 6.8 generated scripts fail with 6.9 the same way the 6.9 generated scripts do
3) If I in 6.9 generate the scripts and replaces the contents of the package script with a bunch of echos (see below), it fails too.
4) If I cut the number of echos in half, the script finishes.
I believe the amount of output the script generates triggers a problem in the execution code.
Will reassign to execution component and akrasny.

----------------------------------------------------
#!/bin/bash -x

#
# Generated - do not edit!
#

# Macros
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx

echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx
echo xxxxxxxxxxxxxxxxxxxxxxxxx 
----------------------------------------------------

Starting showstopper process.

fixed in cnd-main.
http://hg.netbeans.org/cnd-main/rev/15b53e8bf0f9

Alex, review, please.

Fix right and safe

verified in dev cnd build from bertram.
please push to release69 clone.

Integrated in release69:
http://hg.netbeans.org/release69/rev/743342498b0a

"Build Packaging" tests worked in such build from Netbeans.org
Product Version         = NetBeans Platform Dev (Build 201005132200) (#fd91a0b3b548)

And tests failed in next public build:
Product Version         = NetBeans Platform Dev (Build 201005170932) (#954bcc54af95)

verified in rc1 build