$ git init
Initialized empty Git repository in /.../git-history/.git/
$ mkdir dir1

$ nano dir1/file.txt                                   # File version 1
$ git add dir1/file.txt
$ git commit -m "First version of the file"
[master (root-commit) 27a260b] First version of the file
1 file changed, 2 insertions(+)
create mode 100644 dir1/file.txt

$ nano dir1/file.txt                                  # File version 2
$ git commit -am "Second version of the file"
[master bab5759] Second version of the file
1 file changed, 1 insertion(+), 1 deletion(-)

$ git mv dir1 dir2                                   # Move the file around
$ git commit -m "dir1 -> dir2"
[master c9d9b87] dir1 -> dir2
1 file changed, 0 insertions(+), 0 deletions(-)
rename {dir1 => dir2}/file.txt (100%)

$ nano dir2/file.txt                                 # File version 3
$ git commit -am "Third version of the file"
[master 2c3506e] Third version of the file
1 file changed, 1 insertion(+), 1 deletion(-)

$ git log dir2/file.txt                              # git log without follow omits history
commit 2c3506eb4ebb62e164522aa50196e5d47d2e4ffd
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:46 2012 -0500
Third version of the file

commit c9d9b87c8fefd5bc1ba64b6fb9944df138981a4a
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:24 2012 -0500

dir1 -> dir2

$ git log --follow dir2/file.txt                     # but git log --follow includes it
commit 2c3506eb4ebb62e164522aa50196e5d47d2e4ffd
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:46 2012 -0500

Third version of the file

commit c9d9b87c8fefd5bc1ba64b6fb9944df138981a4a
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:24 2012 -0500

dir1 -> dir2

commit bab57593d60a25206bd987e9be3a42fd4d917b70
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:06 2012 -0500

Second version of the file

commit 27a260b1ae80ad7d96e9d802d2dd83dd0c9be18e
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:15:51 2012 -0500

First version of the file

$ git filter-branch --subdirectory-filter dir2 -- --all      # filter that directory
Rewrite 2c3506eb4ebb62e164522aa50196e5d47d2e4ffd (2/2)
Ref 'refs/heads/master' was rewritten

$ ls
file.txt

$ git log file.txt                                   # git log without follow omits history
commit 65fee0bb46885e15648a11f6e5676a3a606c5a2f      # (as expected)
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:46 2012 -0500

Third version of the file

commit 5c56a9bf5ea86eb4b32f47fd62cca64a9c6a8171
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:24 2012 -0500

dir1 -> dir2

$ git log --follow file.txt                         # but now git log --follow also omits
commit 65fee0bb46885e15648a11f6e5676a3a606c5a2f     # history
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:46 2012 -0500

Third version of the file

commit 5c56a9bf5ea86eb4b32f47fd62cca64a9c6a8171
Author: Evan Driscoll <driscoll@cs.wisc.edu>
Date: Tue Sep 4 17:16:24 2012 -0500

dir1 -> dir2