Add ability to not save mtime in metadata files

If you're storing metadata in a version control system with multiple
branches, mtime differences are going to produce a whole bunch of
conflicts that you likely don't care about. This allows you to not
save mtime and avoid those.

Note that we use a sentinel value of -1 for the mentry `mtimensec` field
to indicate this in the data, as all values of `mtime` are theoretically
valid, but `mtimensec` must always be between 0 and 999,999,999 in the
real world.

I'm not 100% sure about the mechanism for selecting this feature. The
legacy behaviour for metastore was to save mtimes in the metadata files,
but ignore them for compare/apply by default, with a `--mtime` option to
use the mtime data.

Keeping the legacy behaviour for backwards compatibility, but adding a
`--no-mtime` option to ignore mtimes when saving felt like a reasonable
way of making this happen, but something about it doesn't feel great.

Maybe I just didn't figure out how to make the documentation clear
enough.  ¯\_(ツ)_/¯

1 files changed, 4 insertions, 1 deletions

diff --git a/man1/metastore.1 b/man1/metastore.1
index 1e01daf..ee01dd8 100644
--- a/man1/metastore.1
+++ b/man1/metastore.1
@@ -51,6 +51,9 @@ once for even less verbosity.
 .B \-m, \-\-mtime
 Causes metastore to also take mtime into account for the compare or apply actions.
 .TP
+.B \-M, \-\-no\-mtime
+Causes metastore to not save mtime in the metadata
+.TP
 .B \-e, \-\-empty\-dirs
 Also attempts to recreate missing empty directories. May be useful where
 empty directories are not tracked (e.g. by git or cvs).
@@ -108,7 +111,7 @@ in
 and
 .I mtime
 is the ISO-8601 extended format representation of the last-modified time in UTC,
-with nanosecond precision.
+with nanosecond precision, or a literal "0" if mtime is not saved.
 
 Strings are URL-encoded, and all characters from 0x00 to 0x20 (inclusive), 0x25
 (%) and 0x7F \fBmust\fR be encoded.