repair: move check for existing transaction earlier
Several benefits:
* Gets close the comment describing it
* Splits off unrelated comment about "backup" argument
* Error checking is customarily done early
* If we added an early return to the method, it would still
consistently fail if there was an existing transaction (so
we would find and fix that case quickly)
One test needs updating with for this change, because we no longer
create the backup bundle before we fail. I don't see much reason to
create that backup bundle. If some command was adding content and then
trying to strip it as well within the transaction, we would have a
backup for the user, but the risk of that not being discovered in
development seems very small.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
> drawdag=$TESTDIR/drawdag.py
>
> [phases]
> publish=False
>
> [alias]
> tglog = log -G --template "{rev}: {desc}"
> EOF
$ rebasewithdag() {
> N=`$PYTHON -c "print($N+1)"`
> hg init repo$N && cd repo$N
> hg debugdrawdag
> hg rebase "$@" > _rebasetmp
> r=$?
> grep -v 'saved backup bundle' _rebasetmp
> [ $r -eq 0 ] && hg tglog
> cd ..
> return $r
> }
Single branching point, without merge:
$ rebasewithdag -b D -d Z <<'EOS'
> D E
> |/
> Z B C # C: branching point, E should be picked
> \|/ # B should not be picked
> A
> |
> R
> EOS
rebasing 3:d6003a550c2c "C" (C)
rebasing 5:4526cf523425 "D" (D)
rebasing 6:b296604d9846 "E" (E tip)
o 6: E
|
| o 5: D
|/
o 4: C
|
o 3: Z
|
| o 2: B
|/
o 1: A
|
o 0: R
Multiple branching points caused by selecting a single merge changeset:
$ rebasewithdag -b E -d Z <<'EOS'
> E
> /|
> B C D # B, C: multiple branching points
> | |/ # D should not be picked
> Z | /
> \|/
> A
> |
> R
> EOS
rebasing 2:c1e6b162678d "B" (B)
rebasing 3:d6003a550c2c "C" (C)
rebasing 6:5251e0cb7302 "E" (E tip)
o 6: E
|\
| o 5: C
| |
o | 4: B
|/
o 3: Z
|
| o 2: D
|/
o 1: A
|
o 0: R
Rebase should not extend the "--base" revset using "descendants":
$ rebasewithdag -b B -d Z <<'EOS'
> E
> /|
> Z B C # descendants(B) = B+E. With E, C will be included incorrectly
> \|/
> A
> |
> R
> EOS
rebasing 2:c1e6b162678d "B" (B)
rebasing 5:5251e0cb7302 "E" (E tip)
o 5: E
|\
| o 4: B
| |
| o 3: Z
| |
o | 2: C
|/
o 1: A
|
o 0: R
Rebase should not simplify the "--base" revset using "roots":
$ rebasewithdag -b B+E -d Z <<'EOS'
> E
> /|
> Z B C # roots(B+E) = B. Without E, C will be missed incorrectly
> \|/
> A
> |
> R
> EOS
rebasing 2:c1e6b162678d "B" (B)
rebasing 3:d6003a550c2c "C" (C)
rebasing 5:5251e0cb7302 "E" (E tip)
o 5: E
|\
| o 4: C
| |
o | 3: B
|/
o 2: Z
|
o 1: A
|
o 0: R
The destination is one of the two branching points of a merge:
$ rebasewithdag -b F -d Z <<'EOS'
> F
> / \
> E D
> / /
> Z C
> \ /
> B
> |
> A
> EOS
nothing to rebase
[1]
Multiple branching points caused by multiple bases (issue5420):
$ rebasewithdag -b E1+E2+C2+B1 -d Z <<'EOS'
> Z E2
> | /
> F E1 C2
> |/ /
> E C1 B2
> |/ /
> C B1
> |/
> B
> |
> A
> |
> R
> EOS
rebasing 3:a113dbaa660a "B1" (B1)
rebasing 5:06ce7b1cc8c2 "B2" (B2)
rebasing 6:0ac98cce32d3 "C1" (C1)
rebasing 8:781512f5e33d "C2" (C2)
rebasing 9:428d8c18f641 "E1" (E1)
rebasing 11:e1bf82f6b6df "E2" (E2)
o 12: E2
|
o 11: E1
|
| o 10: C2
| |
| o 9: C1
|/
| o 8: B2
| |
| o 7: B1
|/
o 6: Z
|
o 5: F
|
o 4: E
|
o 3: C
|
o 2: B
|
o 1: A
|
o 0: R
Multiple branching points with multiple merges:
$ rebasewithdag -b G+P -d Z <<'EOS'
> G H P
> |\ /| |\
> F E D M N
> \|/| /| |\
> Z C B I J K L
> \|/ |/ |/
> A A A
> EOS
rebasing 2:dc0947a82db8 "C" (C)
rebasing 8:215e7b0814e1 "D" (D)
rebasing 9:03ca77807e91 "E" (E)
rebasing 10:afc707c82df0 "F" (F)
rebasing 13:018caa673317 "G" (G)
rebasing 14:4f710fbd68cb "H" (H)
rebasing 3:08ebfeb61bac "I" (I)
rebasing 4:a0a5005cec67 "J" (J)
rebasing 5:83780307a7e8 "K" (K)
rebasing 6:e131637a1cb6 "L" (L)
rebasing 11:d6fe3d11d95d "M" (M)
rebasing 12:fa1e02269063 "N" (N)
rebasing 15:448b1a498430 "P" (P tip)
o 15: P
|\
| o 14: N
| |\
o \ \ 13: M
|\ \ \
| | | o 12: L
| | | |
| | o | 11: K
| | |/
| o / 10: J
| |/
o / 9: I
|/
| o 8: H
| |\
| | | o 7: G
| | |/|
| | | o 6: F
| | | |
| | o | 5: E
| | |/
| o | 4: D
| |\|
+---o 3: C
| |
o | 2: Z
| |
| o 1: B
|/
o 0: A
Slightly more complex merge case (mentioned in https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-November/091074.html):
$ rebasewithdag -b A3+B3 -d Z <<'EOF'
> Z C1 A3 B3
> | / / \ / \
> M3 C0 A1 A2 B1 B2
> | / | | | |
> M2 M1 C1 C1 M3
> |
> M1
> |
> M0
> EOF
rebasing 4:8817fae53c94 "C0" (C0)
rebasing 6:06ca5dfe3b5b "B2" (B2)
rebasing 7:73508237b032 "C1" (C1)
rebasing 9:fdb955e2faed "A2" (A2)
rebasing 11:1b2f368c3cb5 "A3" (A3)
rebasing 10:0a33b0519128 "B1" (B1)
rebasing 12:bd6a37b5b67a "B3" (B3 tip)
o 12: B3
|\
| o 11: B1
| |
| | o 10: A3
| | |\
| +---o 9: A2
| | |
| o | 8: C1
| | |
o | | 7: B2
| | |
| o | 6: C0
|/ /
o | 5: Z
| |
o | 4: M3
| |
o | 3: M2
| |
| o 2: A1
|/
o 1: M1
|
o 0: M0
Disconnected graph:
$ rebasewithdag -b B -d Z <<'EOS'
> B
> |
> Z A
> EOS
nothing to rebase from 112478962961 to 48b9aae0607f
[1]
Multiple roots. Roots are ancestors of dest:
$ rebasewithdag -b B+D -d Z <<'EOF'
> D Z B
> \|\|
> C A
> EOF
rebasing 2:112478962961 "B" (B)
rebasing 3:b70f76719894 "D" (D)
o 4: D
|
| o 3: B
|/
o 2: Z
|\
| o 1: C
|
o 0: A
Multiple roots. One root is not an ancestor of dest:
$ rebasewithdag -b B+D -d Z <<'EOF'
> Z B D
> \|\|
> A C
> EOF
nothing to rebase from 86d01f49c0d9+b70f76719894 to 262e37e34f63
[1]
Multiple roots. One root is not an ancestor of dest. Select using a merge:
$ rebasewithdag -b E -d Z <<'EOF'
> E
> |\
> Z B D
> \|\|
> A C
> EOF
rebasing 2:86d01f49c0d9 "B" (B)
rebasing 5:539a0ff83ea9 "E" (E tip)
o 5: E
|\
| o 4: B
| |\
| | o 3: Z
| | |
o | | 2: D
|/ /
o / 1: C
/
o 0: A
Multiple roots. Two children share two parents while dest has only one parent:
$ rebasewithdag -b B+D -d Z <<'EOF'
> Z B D
> \|\|\
> A C A
> EOF
rebasing 2:86d01f49c0d9 "B" (B)
rebasing 3:b7df2ca01aa8 "D" (D)
o 4: D
|\
+---o 3: B
| |/
| o 2: Z
| |
o | 1: C
/
o 0: A