Yes, it will fail.  For example:

Austins-MacBook-Pro-3:nupic amarshall$ $NUPIC/build.sh
Warning: directory "/Users/amarshall/nta/eng" already exists and may
contain (old) data. Consider removing it.
Warning: directory "/Users/amarshall/ntabuild" already exists and may
contain (old) data. Consider removing it.
~/ntabuild ~/nta/nupic
Updated 6 libraries in arch darwin64
Generating build files for unix
/Users/amarshall/nta/nupic/build_system/post_build
/Users/amarshall/nta/nupic/lang/py/bindings/engine_internal
/Users/amarshall/nta/nupic/lang/py/support
/Users/amarshall/nta/nupic/nta/algorithms
/Users/amarshall/nta/nupic/nta/apps/htmtest
/Users/amarshall/nta/nupic/nta/engine
/Users/amarshall/nta/nupic/nta/math
/Users/amarshall/nta/nupic/nta/ntypes
/Users/amarshall/nta/nupic/nta/os
/Users/amarshall/nta/nupic/nta/regions
/Users/amarshall/nta/nupic/nta/test
/Users/amarshall/nta/nupic/nta/types
/Users/amarshall/nta/nupic/nta/utils
/Users/amarshall/nta/nupic/py/bindings/algorithms
/Users/amarshall/nta/nupic/py/bindings/iorange
/Users/amarshall/nta/nupic/py/bindings/math
/Users/amarshall/nta/nupic/py/cpp_region
/Users/amarshall/nta/nupic/qa/testeverything
Processed 18 projects
Done generating build files for unix
Running autogen...
Done
Ignoring indexes: file:///dev/null
Downloading/unpacking pytest==2.3.5 (from -r
/Users/amarshall/nta/nupic/external/common/requirements.txt (line 3))
  Running setup.py egg_info for package pytest
Downloading/unpacking pytest-cov==1.6 (from -r
/Users/amarshall/nta/nupic/external/common/requirements.txt (line 4))
  Running setup.py egg_info for package pytest-cov
Downloading/unpacking pytest-xdist==1.8 (from -r
/Users/amarshall/nta/nupic/external/common/requirements.txt (line 5))
  Could not find any downloads that satisfy the requirement
pytest-xdist==1.8 (from -r
/Users/amarshall/nta/nupic/external/common/requirements.txt (line 5))
No distributions at all found for pytest-xdist==1.8 (from -r
/Users/amarshall/nta/nupic/external/common/requirements.txt (line 5))
Storing complete log in /Users/amarshall/Library/Logs/pip.log


On Thu, Jul 25, 2013 at 10:14 AM, vitaly-krugl <notifications@github.com>wrote:

> In build.sh:
>
> > @@ -54,7 +54,7 @@ function prepDirectories {
> >
> >  function pythonSetup {
> >      python "$NUPIC/build_system/setup.py" --autogen
> > -    PATH=$NUPIC_INSTALL:$PATH pip install --target=$NUPIC_INSTALL/lib/python2.6/site-packages -r $NUPIC/external/common/requirements.txt
> > +    PATH=$NUPIC_INSTALL:$PATH pip install  --find-links=file://$NUPIC/external/common/pip-cache --no-index --index-url=file:///dev/null --target=$NUPIC_INSTALL/lib/python2.6/site-packages -r $NUPIC/external/common/requirements.txt
>
> @oxtopus <https://github.com/oxtopus>: does the build fail if the
> required package, say pytest-xdist, is missing from
> $NUPIC/external/common/pip-cache?
>
> —
> Reply to this email directly or view it on GitHub<https://github.com/numenta/nupic/pull/138/files#r5403585>
> .
>