use-copy-link changes WORKDIR when used with GIT CLONE

[alexcb]

VERSION --use-copy-link 0.6
FROM alpine:3.15

WORKDIR /test

gitclone:
    RUN test "$(pwd)" = "/test"
    GIT CLONE --branch main https://github.com/earthly/earthly repo
    RUN test "$(pwd)" = "/test" || (echo "pwd=$(pwd) instead of /test" && exit 1) # this fails

failure:

/h/a/t/workdir-not-inherited+base | --> FROM alpine:3.15
/h/a/t/workdir-not-inherited+base | [----------] 100% resolve docker.io/library/alpine:3.15@sha256:cf34c62ee8eb3fe8aa24c1fab45d7e9d12768d945c3f5a6fd6a63d901e898479
/h/a/t/workdir-not-inherited+base | --> WORKDIR /test
/h/a/t/w/earthly)(git@github.com:earthly/earthly) | --> GIT CLONE (--branch main) git@github.com:earthly/earthly
/h/a/t/workdir-not-inherited+gitclone | --> RUN test "$(pwd)" = "/test"
/h/a/t/w/earthly)(git@github.com:earthly/earthly) | 416dce0cf5a1eb2e635ff18b30436fb7d9b05a09	refs/heads/main
/h/a/t/workdir-not-inherited+gitclone | --> COPY GIT CLONE (--branch main) git@github.com:earthly/earthly TO repo
/h/a/t/workdir-not-inherited+gitclone | [----------] 100% merging
/h/a/t/workdir-not-inherited+gitclone | --> RUN test "$(pwd)" = "/test" || (echo "pwd=$(pwd)" && exit 1)
/h/a/t/workdir-not-inherited+gitclone | pwd=/
/h/a/t/workdir-not-inherited+gitclone | ERROR /home/alex/test/workdir-not-inherited/Earthfile line 9:4
/h/a/t/workdir-not-inherited+gitclone |       The command
/h/a/t/workdir-not-inherited+gitclone |           RUN test "$(pwd)" = "/test" || (echo "pwd=$(pwd)" && exit 1)
/h/a/t/workdir-not-inherited+gitclone |       did not complete successfully. Exit code 1

============================ ❌ FAILURE [2. Build 🔧] ============================

[alexcb]

here's a similar failure-case, but using the COPY --keep-own option:

VERSION --use-copy-link 0.6
FROM alpine:3.15

WORKDIR /testwd

data:
    RUN echo data > data
    SAVE ARTIFACT data

copy:
    RUN test "$(pwd)" = "/testwd"
    COPY --keep-own +data/data .
    RUN test "$(pwd)" = "/testwd" || (echo "pwd=$(pwd) instead of /testwd" && exit 1)

[alexcb]

fix in #2546