make_manual: Support SOURCE_DATE_EPOCH

The documentation contains an embedded datetime which do not read
SOURCE_DATE_EPOCH. This makes the documentation unreproducible when
distribution tries to recreate previous build of the package.

This patch ensures we attempt to read the environment variable before
default to the current build time.

Signed-off-by: Morten Linderud <morten@linderud.pw>

bin/make_manual.py

@@ -6,6 +6,7 @@ conversion into man pages etc.
 
 import os
 import re
+import time
 from datetime import datetime
 
 docpath = "docs/content"
@@ -156,17 +157,19 @@ def read_commands(docpath):
         if command != "rclone.md":
             docs.append(read_command(command))
     return "\n".join(docs)
-    
+
 def main():
     check_docs(docpath)
     command_docs = read_commands(docpath).replace("\\", "\\\\") # escape \ so we can use command_docs in re.sub
+    build_date = datetime.utcfromtimestamp(
+            int(os.environ.get('SOURCE_DATE_EPOCH', time.time())))
     with open(outfile, "w") as out:
         out.write("""\
 %% rclone(1) User Manual
 %% Nick Craig-Wood
 %% %s
 
-""" % datetime.now().strftime("%b %d, %Y"))
+""" % build_date.strftime("%b %d, %Y"))
         for doc in docs:
             contents = read_doc(doc)
             # Substitute the commands into doc.md