Git add -p “Your edited hunk does not apply. Edit again”

[Tanky Woo <wtq1990@gmail.com>]

I asked this question in stackoverflow a few days ago, but get no answer.

link: http://stackoverflow.com/questions/29518944/git-add-p-your-edited-hunk-does-not-apply-
edit-again

---

An example, the original file:

test:
       make clean
       nosetests

clean:
       rm -rf htmlcov
       rm -rf build dist
       coverage erase
The file after changed:

HTMLCOV="htmlcov/"

test:
       make clean
       nosetests

clean:
       coverage erase
       rm -rf htmlcov
       rm -rf build dist

covhtml:
       make clean
       nosetests
       coverage html
       cd ${HTMLCOV} && python -m SimpleHTTPServer
This is the diff:

diff --git a/mf b/mf
index b9ca06e..6316e17 100644
--- a/mf
+++ b/mf
@@ -1,8 +1,16 @@
+HTMLCOV="htmlcov/"            # Hunk 1
+
 test:
        make clean
        nosetests

 clean:
+       coverage erase         # Hunk 2
        rm -rf htmlcov
        rm -rf build dist
-       coverage erase         # Hunk 3
+
+covhtml:
+       make clean
+       nosetests
+       coverage html
+       cd ${HTMLCOV} && python -m SimpleHTTPServer
I use git add -p, want only to add:

+       coverage erase
        rm -rf htmlcov
        rm -rf build dist
-       coverage erase
So I first use s to split hunks, and n to ignore first add,
then use y to add second hunk, the third hunk 
is:

-       coverage erase
+
+covhtml:
+       make clean
+       nosetests
+       coverage html
+       cd ${HTMLCOV} && python -m SimpleHTTPServer
So I use e to manually edit the hunk, I delete all the + lines, it seems:

# Manual hunk edit mode -- see bottom for a quick guide
@@ -6,3 +9,8 @@
        rm -rf htmlcov
        rm -rf build dist
-       coverage erase
# ---
# To remove '-' lines, make them ' ' lines (context).
# To remove '+' lines, delete them.
# Lines starting with # will be removed.
#
# ....
But when I saved, it says:

@@ -6,3 +9,8 @@
        rm -rf htmlcov
        rm -rf build dist
-       coverage erase
+
+covhtml:
+       make clean
+       nosetests
+       coverage html
+       cd ${HTMLCOV} && python -m SimpleHTTPServer
Stage this hunk [y,n,q,a,d,/,K,g,e,?]? e
error: patch failed: mf:1
error: mf: patch does not apply
Your edited hunk does not apply. Edit again (saying "no" discards!) [y/n]?
And then I change to @@ from-file-range to-file-range @@ part to:

@@ -6,3 +9,2 @@
There is still the same problem.

If I first add only the second Hunk, 
and then I run git add -p xxx again, and edit the hunk, 
there is no problem. Why?