docs: describe files-from comments

rsync.1.md

@@ -2390,7 +2390,9 @@ expand it.
 
     The filenames that are read from the FILE are all relative to the source
     dir -- any leading slashes are removed and no ".." references are allowed
-    to go higher than the source dir.  For example, take this command:
+    to go higher than the source dir.  Blank entries are ignored, as are
+    whole-entry comments that start with '`;`' or '`#`'.  For example, take
+    this command:
 
     >     rsync -a --files-from=/tmp/foo /usr remote:/backup
 

testsuite/files-from-depth_test.py

@@ -44,6 +44,32 @@ def seed():
 for rel in unlisted:
     assert_not_exists(TODIR / rel, label=f'--from0 excluded {rel}')
 
+# --- comments: line mode and --from0 both ignore them -----------------------
+rmtree(TODIR)
+(src / '#ignored').write_text('hash ignored\n')
+(src / ';ignored').write_text('semi ignored\n')
+commented = SCRATCHDIR / 'files-commented.lst'
+commented.write_text('\n'.join(['', ';ignored', '#ignored', *listed]) + '\n')
+run_rsync('-a', f'--files-from={commented}', f'{src}/', f'{TODIR}/')
+for rel in listed:
+    assert_same(TODIR / rel, src / rel, label=f'--files-from comment list {rel}')
+for rel in unlisted:
+    assert_not_exists(TODIR / rel, label=f'--files-from comment list excluded {rel}')
+for rel in ['#ignored', ';ignored']:
+    assert_not_exists(TODIR / rel, label=f'--files-from comment list skipped {rel}')
+
+rmtree(TODIR)
+comments0 = SCRATCHDIR / 'files-comments0.lst'
+comments0.write_bytes(
+    b'\0;ignored\0#ignored\0' + b'\0'.join(p.encode() for p in listed) + b'\0')
+run_rsync('-a', '--from0', f'--files-from={comments0}', f'{src}/', f'{TODIR}/')
+for rel in listed:
+    assert_same(TODIR / rel, src / rel, label=f'--from0 comment list {rel}')
+for rel in unlisted:
+    assert_not_exists(TODIR / rel, label=f'--from0 comment list excluded {rel}')
+for rel in ['#ignored', ';ignored']:
+    assert_not_exists(TODIR / rel, label=f'--from0 comment list skipped {rel}')
+
 # --- --exclude-from drops matching files at depth ---------------------------
 seed()
 (src / 'a.skip').write_text('s\n')