diff --git a/.travis.yml b/.travis.yml
index dd39336..291473c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,8 +10,8 @@ before_install:
     - git clone --quiet --depth 1 https://github.com/minrk/travis-wheels travis-wheels
     - 'if [[ $GROUP != js* ]]; then COVERAGE=""; fi'
 install:
-    - pip install "setuptools>=18.5" 
-    - pip install -f travis-wheels/wheelhouse -e file://$PWD#egg=ipython[test] traitlets
+    - pip install "setuptools>=18.5"
+    - pip install -f travis-wheels/wheelhouse -e file://$PWD#egg=ipython[test]
     - pip install codecov
 script:
     - cd /tmp && iptest --coverage xml && cd -
diff --git a/setup.py b/setup.py
index c5a8bf5..7fcc724 100755
--- a/setup.py
+++ b/setup.py
@@ -292,13 +292,17 @@ else:
 setup_args.update(setuptools_extra_args)
 
 
-# loose as `.dev` is suppose to be invalid
-loose_pep440re = re.compile('^(\d+)\.(\d+)\.(\d+((a|b|rc)\d+)?)(\.post\d+)?(\.dev\d*)?$')
 
 def main():
-    import IPython.core.release as r
-    if not loose_pep440re.match(r.version):
-        raise ValueError("Version number '%s' is not valid (should match [N!]N(.N)*[{a|b|rc}N][.postN][.devN])" % r.version)
+    try:
+        # loose as `.dev` is suppose to be invalid
+        print("check version number")
+        loose_pep440re = re.compile('^(\d+)\.(\d+)\.(\d+((a|b|rc)\d+)?)(\.post\d+)?(\.dev\d*)?$')
+        import IPython.core.release as r
+        if not loose_pep440re.match(r.version):
+            raise ValueError("Version number '%s' is not valid (should match [N!]N(.N)*[{a|b|rc}N][.postN][.devN])" % r.version)
+    except:
+        pass
     setup(**setup_args)
 
 if __name__ == '__main__':
diff --git a/setupbase.py b/setupbase.py
index 68b51b2..9d801f4 100644
--- a/setupbase.py
+++ b/setupbase.py
@@ -14,7 +14,7 @@ This includes:
 
 from __future__ import print_function
 
-import errno
+import re
 import os
 import sys
 
@@ -24,10 +24,7 @@ from distutils.command.build_scripts import build_scripts
 from distutils.command.install import install
 from distutils.command.install_scripts import install_scripts
 from distutils.cmd import Command
-from distutils.errors import DistutilsExecError
-from fnmatch import fnmatch
 from glob import glob
-from subprocess import Popen, PIPE
 
 from setupext import install_data_ext
 
@@ -426,6 +423,14 @@ def git_prebuild(pkg_dir, build_cmd=build_py):
     class MyBuildPy(build_cmd):
         ''' Subclass to write commit data into installation tree '''
         def run(self):
+            # loose as `.dev` is suppose to be invalid
+            print("check version number")
+            loose_pep440re = re.compile('^(\d+)\.(\d+)\.(\d+((a|b|rc)\d+)?)(\.post\d+)?(\.dev\d*)?$')
+            import IPython.core.release as r
+            if not loose_pep440re.match(r.version):
+                raise ValueError("Version number '%s' is not valid (should match [N!]N(.N)*[{a|b|rc}N][.postN][.devN])" % r.version)
+
+
             build_cmd.run(self)
             # this one will only fire for build commands
             if hasattr(self, 'build_lib'):