I've encountered this particular error while trying to run ota_target_from_phone.

The terminal error is given below:

Build full ota package: /home/ishtiaque/patchrom/xblade/stockrom.zip
Traceback (most recent call last):
File "/home/ishtiaque/patchrom/tools/releasetools/ota_from_target_files", line 76, in
import common
File "/home/ishtiaque/patchrom/tools/releasetools/common.py", line 42, in
OPTIONS.search_path = os.path.join(os.environ["$PORT_ROOT"], "tools");
File "/usr/lib/python2.7/UserDict.py", line 23, in getitem
raise KeyError(key)
KeyError: '$PORT_ROOT'

As you can see, it seems there's a certain issue with the $PORT_ROOT thing. Please look into it and provide solution. Do I need to edit envsetup.sh in any way?