Make handling of setuptools-scm in setup more robust

Fixes #181

setup.py

@@ -19,26 +19,8 @@ requirements_setup = read_req('setup.txt')
 requirements_validation = read_req('validation.txt')
 
 
-try:
-    # this is a workaround for being able to install the package from source without working from a git checkout
-    # it is needed for building succesfully on Heroku
-    from setuptools_scm import get_version
-except ImportError:
-    get_version = None
-
-try:
-    version = get_version()
-    version_kwargs = {'use_scm_version': True}
-except Exception:
-    if any(any(dist in arg for dist in ['sdist', 'bdist']) for arg in sys.argv):
-        raise
-
-    import time
-    timestamp_ms = int(time.time() * 1000)
-    timestamp_str = hex(timestamp_ms)[2:].zfill(16)
-    version_kwargs = {'version': '0.0.0rc0+dummy.' + timestamp_str}
-
-setup(
+def drf_yasg_setup(**kwargs):
+    setup(
         name='drf-yasg',
         packages=find_packages('src'),
         package_dir={'': 'src'},
@@ -78,5 +60,25 @@ setup(
             'Topic :: Documentation',
             'Topic :: Software Development :: Code Generators',
         ],
-    **version_kwargs
-)
+        **kwargs
+    )
+
+
+try:
+    drf_yasg_setup(use_scm_version=True)
+except LookupError as e:
+    if os.getenv('CI', 'false') == 'true' or os.getenv('TRAVIS', 'false') == 'true':
+        raise
+
+    if 'setuptools-scm' in str(e):
+        import time
+
+        timestamp_ms = int(time.time() * 1000)
+        timestamp_str = hex(timestamp_ms)[2:].zfill(16)
+        dummy_version = '0.0.0rc0+noscm' + timestamp_str
+
+        drf_yasg_setup(version=dummy_version)
+        print(str(e), file=sys.stderr)
+        print("failed to detect version, build was done using dummy version " + dummy_version, file=sys.stderr)
+    else:
+        raise