Disable version detection (from git) via env/args

When packaging for distributions, source code is often managed through
some local revision which may-or-may-not be compatible with the version
detection scheme that is designed for upstream. In these cases it's
useful to quickly enable/disable the version detection.

CMakeLists.txt

@@ -6,7 +6,11 @@ include(CheckIncludeFile)
 include(CTest)
 include(GNUInstallDirs)
 
-if (EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/.git)
+if (DEFINED ENV{SEGYIO_NO_GIT_VER})
+    set(SEGYIO_NO_GIT_VER CACHE BOOL "Ignore version from git" ON)
+endif ()
+
+if (EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/.git AND NOT SEGYIO_NO_GIT_VER)
     find_program(git-bin git)
     execute_process(COMMAND ${git-bin} describe --tags
                     OUTPUT_VARIABLE git-describe

changelog.md

@@ -1,3 +1,6 @@
+# 1.3.7
+* Makefiles can turn off version detection from git from env or via args
+
 # 1.3.6
 * Applications no longer spuriously ignore arguments
 * All assertClose calls in tests have non-zero epsilon

setup.py

@@ -57,11 +57,14 @@ def getversion():
     # if this is a tarball distribution, the .git-directory won't be avilable
     # and setuptools_scm will crash hard. good tarballs are built with a
     # pre-generated version.py, so parse that and extract version from it
-    if os.path.isdir(src('.git')):
+    #
+    # set the SEGYIO_NO_GIT_VER environment variable to ignore a version from
+    # git (useful when building for debian or other distributions)
+    if not 'SEGYIO_NO_GIT_VER' in os.environ and os.path.isdir(src('.git')):
         return {
             'use_scm_version': {
-                        'root': src(''),
-                        'write_to': src('python/segyio/version.py')
+                'root': src(''),
+                'write_to': src('python/segyio/version.py')
             }
         }