Use git stash to protect setuptools_scm from RTD.

.readthedocs.yml

@@ -11,6 +11,12 @@ build:
       # to allow setuptools-scm to correctly auto-discover the version.
       - git fetch --unshallow
       - git fetch --all
+    # Need to stash the local changes that Read the Docs makes so that
+    #  setuptools_scm can generate the correct Iris version.
+    pre_install:
+      - git stash
+    post_install:
+      - git stash apply
 
 conda:
   environment: requirements/ci/readthedocs.yml

docs/src/conf.py

@@ -85,17 +85,7 @@ def autolog(message):
 
 # The version info for the project you're documenting, acts as replacement for
 # |version|, also used in various other places throughout the built documents.
-
-if on_rtd:
-    # Get the version string that was generated when RTD installed Iris - RTD
-    #  later modifies Iris' source, causing setuptools_scm to advance the
-    #  version string away from its correct value.
-    from iris._version import __version__
-
-    version = __version__
-else:
-    version = get_version("scitools-iris")
-
+version = get_version("scitools-iris")
 release = version
 autolog(f"Iris Version = {version}")
 autolog(f"Iris Release = {release}")