Split make_file back out into make_filename and make_file.
It turns out that make_filename is useful by itself.
+ mkdir t
+ cd t
+ hg init
+ echo This is file a1
+ hg add a
+ hg commit -t 'commit #0' -d '0 0' -u user
+ echo This is file b1
+ hg add b
+ hg commit -t 'commit #1' -d '0 0' -u user
+ rm b
+ hg update 0
+ echo This is file b2
+ hg add b
+ hg commit -t 'commit #2' -d '0 0' -u user
+ cd ..
+ /bin/rm -rf t
+ mkdir t
+ cd t
+ hg init
+ echo This is file a1
+ hg add a
+ hg commit -t 'commit #0' -d '0 0' -u user
+ echo This is file b1
+ hg add b
+ hg commit -t 'commit #1' -d '0 0' -u user
+ rm b
+ hg update 0
+ echo This is file b2
+ hg commit -A -t 'commit #2' -d '0 0' -u user
+ cd ..
+ /bin/rm -rf t
+ mkdir t
+ cd t
+ hg init
+ echo This is file a1
+ hg add a
+ hg commit -t 'commit #0' -d '0 0' -u user
+ echo This is file b1
+ hg add b
+ hg commit -t 'commit #1' -d '0 0' -u user
+ rm b
+ hg remove b
+ hg update 0
+ echo This is file b2
+ hg commit -A -t 'commit #2' -d '0 0' -u user
+ cd ..
+ /bin/rm -rf t